The talented 23-year-old joins the Stags following an exceptional individual campaign with the Moors.
Sterling-James was part of the Birmingham City academy but was released in the summer of 2012.
He resurrected his career with a spell at Midland League Premier Division outfit Alvechurch before moving for a successful season at Redditch United in the Southern Premier Division.
It was there that he was spotted by Cheltenham Town and after a trial at Whaddon Road he signed a contract that saw him stay until the end of the 2015/16 season.
He made twenty-two appearances for the Robins after his debut against Portsmouth. However, in December the club advised him that the contract would not be renewed further and a spell on loan at Oxford City and then Gloucester City followed before he joined Solihull in July 2016.
He made twenty-nine appearances last season, scored 9 goals and had six assists.
That earned him a call-up for the St Kitts & Nevis national side at the beginning of this month and he made his international debut in a friendly against Armenia.
A number of other clubs in League One and Two were interested in Sterling-James, but The Stags won the race for his services.