Sir Robert Knollys (1588–1659) was an English politician who sat in the House of Commons between 1614 and 1629.
Knollys was the 2nd son of Richard Knollys of Stanford-in-the-Vale in Berkshire (now Oxfordshire). He matriculated at Oriel College, Oxford on 13 May 1603, aged 15. He was knighted on 12 January 1613.
In 1614, he was elected Member of Parliament for Abingdon. He was elected MP for Berkshirein 1621. In 1624 he was elected MP for Abingdon again, and was re-elected in 1625 and 1626. In 1628 he was elected MP for Wallingfordand sat until 1629 when King Charles decided to rule without parliament for eleven years.
Knollys bought Greys Court from his uncle, William Knollys, Earl of Banbury, died at the age of about 70 and was buried on 26 June 1659.
He married Joan, the daughter of Sir John Wolstenholme and left a son and several daughters.