His work included one of the first railway bridges in the UK (over the River Skerne, near Darlington), for the Stockton and Darlington Railway, in 1824 (hence he is sometimes referred to as 'the first railway architect').
He was also responsible for a number of church buildings (including commissions at Durham Cathedral) and historic buildings in Gothic and neo-classical styles, including Durham Castle, Lambton Castle and Burn Hall in County Durham.
In 1831, Bonomi took on John Loughborough Pearson as an apprentice. In 1842 he entered into a partnership with John Augustus Cory.