Carew was rumoured to have inherited a £10,000 fortune when he succeeded his father at the age of 14. However, his only significant source of income was the prothonotaryship of Chancery, to which he was granted the reversion in 1611. From 1614 until he came of age this office was exercised on his behalf by his uncle (Sir) Francis Godolphin* and John Packer*.
From 1624 to 1626 Carew sat for Helston in three consecutive parliaments on the interest of Sir Francis Godolphin, but he apparently contributed little to their proceedings. Indeed, the last Jacobean Parliament was still sitting when Prince Charles sent him to The Hague in late March 1624 to notify the Electress Palatine of the breach with Spain. During the Cadiz expedition of 1625, Carew not only contributed a barque, which was lost in a storm, but served aboard the flagship, the Anne Royal, as captain of the guard to Sir Edward Cecil*.
Carew captained a prize ship, the Esperance, during the 1627 expedition to the Île de Ré, retaining his command until the following January.
