Starting his career at Real Zaragoza, Antwi joined Liverpool in 2005 but he is yet to make a senior appearance for the Merseyside club. However, he has spent time on loan at two clubs over the last two seasons, spending three months at Accrington Stanley during the 2006-07 season, making nine appearances for the Lancashire club, before spending the whole of last season at Hartlepool, where he made 34 appearances, scoring once. He played once against Tranmere last season, helping Hartlepool to a 3-1 Tuesday night win over Rovers at Victoria Park.
Antwi, who was born in Ghana, has been a successful part of the Liverpool reserve team over recent years, picking up a F.A. Youth Cup winners medal with the club in 2006.
The signing comes after Ronnie Moore confirmed he would look at bringing youngsters across the water to Prenton Park to help fill out his squad,, with Antwi becoming Tranmere's first loan signing from Liverpool since David Raven joined in 2005-06.
The youngster will take the Number 2 shirt vacated by Robbie Stockdale at the end of last season.