The 24-year-old is available on a Bosman free transfer and reports suggest that he is due to undergo a medical at Thorp Arch tomorrow, after which he is expected to join the club.
Clarke made 33 appearances for QPR last season having joined them four years ago for a fee of £250k from Blackpool.
A former England U-21 international, Carlisle is 6ft 3in and came through the ranks at Blackpool.
He becomes Rangers sixth departure this summer.