Brock was born in Worcester, attended the School of Design in Worcester and then undertook an apprenticeship in modelling at the Worcester Royal Porcelain Works. In 1866 he became a pupil of the sculptor John Henry Foley. He married in 1869, and had 8 children. After Foley's death in 1874, Brock completed some of his commissions.
He first came to prominence when he was asked to complete the statue of Prince Albert for the Albert Memorial. In 1901 Brock was awarded the colossal equestrian statue of Edward the Black Prince, set up in the City Square in Leeds, and was also given perhaps his most significant commission, the vast multi-figure Imperial Memorial to Queen Victoria in front of Buckingham Palace. According to legend, at the unveiling in May 1911, George V was so moved by the excellence of the memorial that he called for a sword and knighted Brock on the spot.
His group The Moment of Peril (now in the Tate Gallery) was followed by The Genius of Poetry, at the Carlsberg Brewery, in Copenhagen, Eve, and other ideal works that mark his development. Other works include busts, such as those of Lord Leighton and Queen Victoria, statues, such as Sir Richard Owen and Henry Philpott, bishop of Worcester, and sepulchral monuments such as Lord Leighton in St Pauls Cathedral, a work of singular significance, refinement and beauty.
Brock was elected an associate of the Royal Academy in 1883 and full member in 1891.