Browne was descended ultimately from yeoman stock. His ancestors were tenant farmers of the demesnes of Frampton by the reign of Henry VI, though his grandfather bought the manor in the 1570s, having recently been granted arms.
In 1626 Browne was living in Dorchester, where the county elections were held. Unusually, the county gentry failed that year to nominate the two shire knights in advance, and on election day Browne allowed his name to be put forward for the junior seat. Although he enjoyed the support of his friends in Dorchester and many other county freeholders, he found himself at odds with his own brother-in-law, the influential Sir John Strangways*, who was backing a rival candidate, Sir George Morton*. Under pressure from his father, who was reluctant to offend Strangways, Browne himself made a show of withdrawing. His supporters forced a poll regardless, which was then manipulated in Morton’s favour. Accordingly, Robert Browne and others petitioned the Commons on Browne’s behalf, and the election was declared void. The blatant fraud during the first poll had divided the Dorset gentry, and when the second election was held Browne stood again, this time with the backing of his father, father-in-law, brother-in-law Sir Thomas Trenchard*, and Sir Richard Strode*. Once again Morton emerged victorious, and although there was further evidence of underhand dealing, Browne this time opted not to challenge the result.
In 1627 Browne succeeded to the Frampton estate, and an annual income of £1,100. He was returned for Bridport in the following year, but this election was marred by a franchise dispute, and the result was declared void on 12 Apr. 1628, before Browne could take any part in the third Caroline Parliament.
A puritan by conviction, as demonstrated by his membership of the Dorchester New England Company and his private correspondence during the 1630s, Browne disliked the policies of Charles I’s Personal Rule, and defaulted on Ship Money.