He started as a physician and practised for some years, kept a school and studied astronomy. Having removed to London, he was admitted (November 6, 1618) a licentiate of the college of physicians, and was noticed due to a publication concerning the comet of 1618. Sir Henry Savile (1549-1622) then appointed him in 1610 to the Savilian chair of astronomy just founded by him at Oxford; Bainbridge was incorporated of Merton College and became, in 1631 and 1635 respectively, junior and senior reader of Linacre's lectures.
He died at Oxford on the November 3, 1643.
He wrote An Astronomical Description of the late Comet (1619); Canicularia (1648); and translated Proclus' De Sphaera, and Ptolemy's De Planetarum Hypothesibus (1620). Several manuscript works by him exist in the library of Trinity College, Dublin.