Reeves began his singing career in 1838 but continued his vocal studies until 1847. He soon established himself on the opera and concert stage and became known for his interpretation of ballads. He continued singing through the 1880s and later taught and wrote about singing.
He made his earliest appearance at Newcastle in 1838 or 1839 as the Gipsy boy in H. R. Bishop's Guy Mannering, and as Count Rodolfo in La sonnambula (baritone parts). Later he performed at the Grecian Saloon, London, under the name of Johnson. He continued to study voice with Messrs. Hobbs and T. Cooke and appeared under William Charles Macready's management at Drury Lane (1841-1843) in subordinate parts in spoken theatre and in Henry Purcell's King Arthur ("Come if you dare"), Der Freischütz (as Ottokar), and Acis and Galatea in 1842 when Händel's pastoral was mounted on the stage with William Clarkson Stanfield's scenery.
In summer 1843 Reeves studied in Paris under the tenor and pedagogue Marco Bordogni of the Paris Conservatoire. Bordogni was responsible for opening and developing the upper (tenor) octave of his voice into the famous rich and brilliant head notes. From October 1843 to January 1844 Reeves appeared in a very varied programme of musical drama, including the roles of Elvino in La Sonnambula and Tom Tug in Charles Dibdin's The Waterman, at the Manchester theatre, and over the next two years also performed in Dublin, Liverpool and elsewhere in the provinces. In the same period, especially from 1845, he continued his studies abroad, notably under Alberto Mazzucato (1813-1877), the dramatic composer and teacher then newly appointed singing instructor at the Milan Conservatory.
His debut in Italian opera was made on 29 October 1846 at La Scala in Milan as Edgardo in Donizetti's Lucia di Lammermoor, partnered by Catherine Hayes: he got a fine reception, and Giovanni Rubini paid his respects in person. (This role became Reeves's greatest, and his wife therefore nicknamed him 'Gardie'.) For six months he sang at the principal Italian opera houses, and finally in Vienna, where he was rescued from his contract and returned to England.
In oratorio, Reeves first sang The Messiah in Glasgow, Scotland, during 1844. In February 1848 he sang Handel's Judas Maccabaeus, at Exeter Hall for John Hullah, Acis and Galatea in March and Jephtha in April and May. He was, meanwhile establishing himself as the leading ballad-singer in England. In September 1848 at the Worcester festival he took a solo in Elijah, and sang in Beethoven's Christ on the Mount of Olives, and packed the hall in a recital of Oberon. At the Norwich Festival he was sensational in Elijah and Israel in Egypt. After his November appearance at the Sacred Harmonic Society in Judas Maccabaeus, a critic wrote, 'the mantle of Braham is destined to fall' (on Reeves). Critic H. F. Chorley wrote that Reeves had created 'a positive revolution in the interpretation of Handel's oratorios.'
On 2 November 1850, he married Charlotte Emma Lucombe (1823–1895), a soprano who had a brief but brilliant season at the Sacred Harmonic Society and had joined the same company as Reeves at Covent Garden. There she appeared with success as Haydee in Auber's opera, and remained on the stage for four or five years after their marriage. Emma Reeves idolised her husband and in later years became almost obsessively attentive to his comfort and reputation. In February 1851 they returned to Dublin, where Reeves was to have performed with the soprano Giulia Grisi: she, however, was indisposed, and Mr. and Mrs. Reeves appeared together there instead in the lead roles in Lucia di Lammermoor, La Sonnambula, Ernani and Bellini's I Puritani. Reeves also played there Macheath in the Beggar's Opera. Emma and Sims Reeves had five children, of whom Herbert Sims Reeves and Constance Sims Reeves became professional singers.
Dublin was followed immediately by Lumley engagements at the Théâtre des Italiens, Paris, where he sang Ernani, Carlo in Linda di Chamounix (opposite Henriette Sontag) and Gennaro in Donizetti's Lucrezia Borgia. In 1851 Reeves sang Florestan in Fidelio to Cruvelli's Leonore, and outshone her.
Reeves was generous to younger singers, and this generosity later redounded to his own benefit. In around 1850, Reeves gave encouragement to James Henry Mapleson, who applied to him for advice as a singer, sending him off to study with Mazzucato at the Milan conservatory. In 1855 he gave the young Charles Santley friendly encouragement, recommending that he should contact Lamperti in his forthcoming studies in Italy, and they were afterwards introduced during the interval of a Royal Philharmonic concert. Reeves's concert association with Santley continued until the last year of his life. Mapleson, who became an important theatre manager, promoted Reeves's operatic appearances of the 1860s.
During the 1850s, Reeves's career moved away from the stage and increasingly focused upon concert work. Reeves sang throughout the English provinces. Michael Costa (afterwards Sir Michael) composed two oratorios for the triennial Birmingham Festival with lead tenor parts written for Reeves. The first, Eli, was presented in 1855, and (unusually in oratorio) encores were demanded. The effect of the solo and chorus Philistines, Hark the Trumpet Sounding was electric, and was witnessed in the audience by the three great Italian tenors Mario, Gardoni and Enrico Tamberlik with astonishment.
Reeves scored his greatest triumphs in oratorio at the Handel Festivals at The Crystal Palace. At the inaugural festival of June 1857 he delivered Messiah, Israel in Egypt and Judas Maccabaeus, and these were repeated at the Handel centennial festival of 1859, when he was in company with Willoughby Weiss, Clara Novello, Mme Sainton-Dolby and Giovanni Belletti. In Sound an Alarm during that festival, Reeves created a sensation, and the audience stood to applaud him. Yet the Musical World considered that his "The Enemy Said" from Israel in Egypt surpassed even that, and was the vocal feat of the festival.
In 1862, Reeves presented Mazeppa, a cantata written for him by Michael Balfe. In July 1863 Reeves appeared for Mapleson as Huon in Oberon - the role written for Braham - with Tietjens, Marietta Alboni, Zelia Trebelli, Alessandro Bettini, Edouard Gassier and Santley. After touring that winter as Huon, Edgardo and in the title role of Gounod's Faust, (with Tietjens) in Dublin, in 1864 he appeared at Her Majesty's in Faust and was especially complimented for the dramatic instinct of Faust's soliloquy in Act I and the superb energy of the duet with Mephistopheles which closes the Act. Reeves's reviewer in this role remarks on the fine condition of his voice at this date. Although the critic Eduard Hanslick was told that the voice had already 'gone' in 1862, Hermann Klein thought that it was still in its prime in 1866: 'a more exquisite illustration of what is termed the true Italian tenor quality it would be impossible to imagine: and this delicious sweetness, this rare combination of 'velvety' richness with ringing timbre, he retained in diminishing volume almost to the last.'
'The tenor part... is in many places so unvocal, and the intervals are so awkward to take, that I was obliged to re-note it: without, of course, disturbing the accents or making it in any way unsuitable to the existing harmony. As soon as I had finished my work, to which I had devoted the greatest possible care, I submitted it to Bennett, who, except in one place, approved of all that I had done; and it was my version of the tenor part which was sung at Bennett's memorable performance, and which is still sung even to this day.'
In Michael Costa's second oratorio for Reeves, Naaman (first performed autumn 1864), the soloists were Reeves, Adelina Patti (her first appearance in oratorio), Miss Palmer, and Santley. The quartet "Honour and Glory" was repeated by immediate and spontaneous demand. Both oratorios probably owed their original success, and later comparative obscurity, to the fact that Reeves was their ideal interpreter, and with changing vocal fashions no successor could replace him adequately. In 1869 Reeves, Santley and Tietjens sang in the premiere of Arthur Sullivan's cantata The Prodigal Son, at the Worcester Festival. Santley considered Reeves's performance of the passage "I will arise and go to my father" a once-in-a-lifetime experience. Reeves also sang in the premiere of Sullivan's oratorio, The Light of the World, together with with Tietjens, Trebelli, and Santley.
Reeves claimed close and primary association with several of the great tenor leads in the oratorios of Handel and Mendelssohn. The songs "Men, Brothers and Fathers, Hearken to me" (from St Paul), and "The Enemy has Said" and "Sound an Alarm" (Judas Maccabaeus) were particular favourites, and his friend Rev Archer Gurney also extolled his "Waft her, angels" (Jephthah), his Samson and his Acis ("Love in her eyes sits playing").
Reeves continued until the 1880s, without any break, to sing for the Sacred Harmonic Society. In the winter of 1878-1879, he appeared with immense success in The Beggar's Opera and in The Waterman, at Covent Garden. Edward Lloyd, who took Reeves's place as principal tenor at the Handel Festivals, sang with him, and with the tenor Ben Davies, in a performance of the trio for tenor voices 'Evviva Bacco' by Curschmann, at a concert in St James's Hall in 1889.
Reeves's retirement from public life, at first announced as to take place in 1882, did not actually occur until 1891. Then a farewell concert for his benefit was given at the Royal Albert Hall in which Reeves himself performed, supported by Christine Nilsson (who on this occasion refrained from slapping him on the back in congratulation), and at which he received a eulogy from Sir Henry Irving. George Bernard Shaw remarked that even then, in such Handelian airs as Total Eclipse (Samson), 'he can still leave the next best tenor in England an immeasurable distance behind.' The song "Come into the garden, Maud", which Balfe had written for him in 1857, appeared often in his late concerts.
It is certain that Reeves stayed before the public long after his greatest powers had waned. He invested his savings in an unfortunate speculation, and he was compelled to reappear in public for a number of years. In his later career, he frequently withdrew from promised appearances owing to the effects of colds on his fragile vocal equipment, and through an unhappy susceptibility to the effects of nervousness. This also caused him financial difficulties: Besides the loss of income from the engagements, legal judgments for failure to perform were rendered against him, including in 1869 and 1871. The accusation (which gained some currency) that he was given to drink was disavowed by his friend Sir Charles Santley.
In 1890 Shaw stated that Reeves's many cancelled appearances were made entirely for the sake of pure artistic integrity 'which few appreciate fully', but left him at the head of his profession, and had required enormous efforts of artistic conviction, courage, and self-respect. He wrote of a performance of Blumenthal's The Message, 'In spite of all his husbandry, he has but few notes left now; yet the wonderfully telling effect and unique quality of those few still justify him as the one English singer who has worked in his own way, and at all costs, to attain and preserve ideal perfection of tone.'
Klein said much the same as Shaw: 'To hear him, long after he had passed the age of seventy, sing "Adelaide" or "Deeper and Deeper Still" or "The Message" was an exposition of breath control, of tone-colouring, of phrasing and expression, that may truly be described as unique.' Reeves sang in two concerts in the first season of The Proms, at Queen's Hall in 1895 (at which, of course the lower continental pitch was employed). They were the only two concerts of that season that were sold out: all the others made at least £50 loss.
In 1888, Reeves published Sims Reeves, his Life and Recollections, followed by My Jubilee, or, Fifty Years of Artistic Life in 1889. At the same time, he became a teacher at the Guildhall School of Music and Drama. His 1900 book, On the Art of Singing, describes his pedagogic methods. After the death of his wife in 1895, he quickly remarried one of his students, Lucy Maud Madeleine Richard (b. 1873), and the couple toured South Africa the next year. Reeves died in Worthing, England, on 25 October 1900 and was cremated at Woking.
In the Handel tenor roles, his immediate successor in the Crystal Palace performances, until 1900, was the English tenor Edward Lloyd, who recorded "Sound an Alarm", "Lend me your Aid" (Gounod - "Reine de Saba"), the tenor solos from Elijah, Braham's Death of Nelson, Dibdin's Tom Bowling and ballads of the declamatory style (such as Frederic Clay's "I'll sing thee songs of Araby"; "Alice, Where art thou?" and "Come into the Garden, Maud") - all closely identified with Reeves - in the first years of the twentieth century. Lloyd, and his contemporary Ben Davies, both declaim with a marked lack of vibrato, a true attack (without coup de glotte), and portamento, which may echo Reeves's, and perhaps even Braham's style.