The eldest child of Sir Edward Filmer and Elizabeth Filmer (née Argall) of East Sutton in Kent, he matriculated at Trinity College, Cambridge, in 1604. He did not take a degree and was admitted to Lincoln's Inn on 24 January 1605. He was called to the bar in 1613, but there is no evidence he practised law. He bought the porter's lodge at Westminster Abbey for use as his town house. On 8 August 1618 he married Anne Heton in St Leonard's Church in London, with their first child baptised in February 1620. On 24 January 1619, King James I knighted Filmer at Newmarket.