Halls exhibited in 1798 'Fingal assaulting the Spirit of Loda,' in 1799 'Zephyr and Aurora,' and in 1800 'Creon finding Hæmon and Antigone in the Cave.'
Subsequently he chiefly devoted himself to portrait-painting, but he occasionally attempted ambitious subjects, like 'Lot's Wife' (1802), 'Hero and Leander' (1808), and 'Danae' (1811).
A large picture (exhibited at the British Institution in 1813) of 'Christ raising the Daughter of Jairus,' won a premium, of two hundred guineas; it went to the church of St. Peter at Colchester.
A full-length portrait of Charles Kean as Richard III by Halls was also engraved by Turner.
Halls completed in 1813 a stained-glass window for Lichfield Cathedral, a commission which he obtained through his friend, Henry Salt.