John Allan Rolls was the only son of John Etherington Welch Rolls and his wife Elizabeth Mary Long. Elizabeth was a daughter of Walter Long of Preshaw and granddaughter of William Carnegie, 7th Earl of Northesk. Rolls was educated at Eton College and Christ Church, Oxford. He later became a Captain in the Royal Gloucestershire Hussars Yeomanry Cavalry, and was afterwards appointed honorary colonel of the 4th Welsh Brigade R.F.A.

In 1868 he married Georgiana Marcia Maclean in London. She was the daughter of Sir Charles Fitzroy Maclean, 9th Baronet of Morvaren (1798-1883). They had four children:

The Hon. John Maclean Rolls (1870-1916) 2nd Baron Llangattock who died at the Battle of the Somme

The Hon. Henry Alan Rolls (1871-1916)

The Hon. Eleanor Georgiana Rolls (1872-1961) later the Hon. Lady Shelley-Rolls

The Hon. Charles Stewart Rolls (1877-1910) of Rolls Royce fame and the first British aircraft fatality

Rolls served as MP for Monmouthshire from 1880-1885, and was raised to the peerage in 1892. He was elected High Sheriff of Montgomeryshire in 1895 and served as Mayor of Monmouth between 1896 and 1897. He was also a magistrate and Deputy Lieutenant of Monmouthshire. He was created 1st Baron of Llangattock, of the Hendre, county of Monmouthshire, on 30 August 1892.

Rolls was a breeder of Shire horses and acquired a reputation amongst agriculturalists for his shorthorn and Hereford cattle and Shropshire breeds of sheep. He was a fellow of the Society of Antiquaries and restored several Monmouthshire churches at his own expense.

Rolls died on 24 September 1912.