Barlow was born in South Mimms, Hertfordshire, to his father Thomas WIlliam, a Clerk. He was educated at Blundell's School, after which in 1816 he started attending Trinity College, Cambridge. He earned his BA in 1820 and his MA in 1823. In 1822 he became the curate of the parish of Uckfield, Sussex. On 23rd March 1823 he was ordained as a priest. From 1830-1843 he was rector to the parish in Little Bowden, Northamptonshire. In 1824 he married Cecilia Anne Lam.
In 1832 Barlow joined the Royal Institution of Great Britain and he would serve many positions including Manager (1838), Secretary of the Lectures Committee (1841) and Honorary Secretary (1843-1860. Barlow was elected into the Royal Society in 1834 and served as Secretary of the Zoological Society of London from 1837-1838.
In 1851 Barlow became minister of the Duke Street Chapel, London and from 1854-1859 he was Chaplain-in-Ordinary at Kensington Palace.
