Since 1971, he has been a frequent conductor of operas and concerts at the Salzburg Festival, where he is particularly known for his Mozart opera performances. From 1972, Muti regularly conducted the Philharmonia Orchestra in London. In 1974, he was appointed the orchestra's principal conductor to succeed Otto Klemperer.
In 1987, Muti was appointed principal conductor of the Scala Philharmonic Orchestra, with which in 1988 he received the Viotti d'Oro and with which he went on tour in Italy and in Europe. In 1991, he announced his resignation from the Philadelphia Orchestra at the end of the 1991-1992 season.
Muti has been a regular guest of the Berlin Philharmonic and the Vienna Philharmonic. In 1996, Muti conducted the latter at the closing of the Viennese Festival Week in a tour of the Far East to Japan, Korea, Hong Kong, Germany, and the Vienna New Year's Concert in 1993, 1997, 2000 and 2004.
Apart from La Scala, Muti has conducted operatic performances with the Philadelphia Orchestra, as well as productions in Munich, at the Vienna State Opera (starting with Aida in 1973, followed by La forza del destino in 1974, Rigoletto in 1983, Così fan tutte in 1994, Don Giovanni in 1999, Le nozze di Figaro in 2001), in London, and at the Ravenna Festival.
Muti is a regular guest conductor at the Vienna Staatsoper where he continues to conduct Mozart operas such as Le nozze di Figaro and Così fan tutte. He is to return to this opera house in 2008 with Così fan tutte.
A special relationship connects Muti with the Salzburg Festival, where the conductor debuted in 1971 with Donizetti's Don Pasquale. In the following years Muti has been constantly present at the festival, conducting both concerts with the Vienna Philharmonic Orchestra and opera productions, such as Così fan tutte in 1983 and Die Zauberflöte in 2005 and 2006. Muti also owns a residence close to Salzburg.
From 2007 on, Muti is the principal conductor at Salzburg's Pentecost Festival. He conducts opera productions and concerts with his Luigi Cherubini Youth Orchestra.
In the USA, from 1980 to 1992, Muti was music director of the Philadelphia Orchestra, which he led on numerous international tours. In 1979, he was appointed its music director and, in 1992, conductor laureate. Muti stated that his approach was to remain faithful to the intent of the composer. This meant a change from applying the lush "Philadelphia Sound," created by his predecessors Eugene Ormandy and Leopold Stokowski, to all repertoire; however, many of his recordings with that orchestra largely seem to do away with its hallmark sound, even in the works of such composers as Tchaikovsky, Brahms, and other high romantics. His sonic changes to the orchestra remain controversial. Some felt he turned it into a generic-sounding institution with a lean sound much favored by modern recording engineers. Others believe Muti uncovered the true intention of the works, which had been covered in a silky sheen by Muti's predecessor. Since his departure from Philadelphia, he has made very few guest conducting appearances with the Philadelphia Orchestra, most recently in 2005.
Muti has been a regular and popular guest conductor with the New York Philharmonic. The orchestra's musicians have been reported as being interested in Muti as their next music director, both towards the end of the tenures of Kurt Masur and Lorin Maazel, but Muti had stated that he had no wish to take on the position with the orchestra. On May 5, 2008, Muti was named the next music director of the Chicago Symphony Orchestra (CSO), effective with the 2010-2011 season, with an initial contract of 5 years. Muti is scheduled to conduct a minimum of 10 weeks of CSO subscription concerts each season, in addition to domestic and international tours. He made his CSO debut at the Ravinia Festival in 1973.
Riccardo Muti is married to Cristina Mazzavillani, who is the founder and director of the Ravenna Festival. They have three children, two sons and a daughter.
On 24 February 2005, the La Scala governors dismissed Fontana as general manager and named Meli as his successor. The musicians sided with Fontana against Muti at this point in the dispute, and on 13 March, Muti stated that he would refuse to conduct the La Scala orchestra from that point on. On March 16, 2005, the orchestra and staff of La Scala voted overwhelmingly against Muti in a motion of no-confidence. Muti was forced to cancel a concert prior to the vote, and some other productions were disrupted at the theater because of continuing rifts with Fontana's supporters. On April 2, he resigned from La Scala, citing "hostility" from staff members.
Muti is considered one of the world's greatest conductors of the operas of Giuseppe Verdi. He also led a series of annual performances of opera in concerts include the works of the composers Verdi, Puccini, Mozart, and Wagner. In 1992, Muti conducted performances of Ruggero Leoncavallo's Pagliacci with Luciano Pavarotti. A recording was also made of these performances.