He was educated at Trinity College, Cambridge, and was called to the Bar at Gray's Inn, in 1827.
He served in Lord John Russell's first administration as Solicitor-General from 1848 to 1850 and as Attorney-General from 1850 and 1851. The latter year he was appointed Master of the Rolls, a post he held until 1873. Knighted in 1848, he was ennobled as Baron Romilly in 1866.
Romilly first entered Parliament in 1832 as member for Bridport, holding the seat from 1832 to 1835 and again from 1846 to 1847. In 1843 he became a Queen's Counsel. In 1851 he was appointed Master of the Rolls, and continued to sit for Devonport till the general election in 1852, when he was defeated.
He was the last Master of the Rolls to sit in Parliament. Romilly was raised to the peerage as Baron Romilly, of Barry in the County of Glamorgan, in 1866, and retired from the mastership of the rolls in 1873. He did much to remove the restrictions which had long hampered research among the public records and state papers.
Lord Romilly married Caroline Charlotte, daughter of the Right Reverend William Otter, in 1833. They had several children. She died in December 1856.
He is buried in Brompton Cemetery, London.
[11th United Kingdom Parliament. 14th United Kingdom Parliament. 15th United Kingdom Parliament]
He was elected Member of Parliament for Devonport in 1847, and was appointed Solicitor-General and knighted in 1848 in Lord John Russell's administration, being promoted to Attorney-General in 1850.