Vassell began his career with Stoke City having been spotted as a youngster playing for Hanley Town, and spent almost a decade with the Potters.
In 2015 he signed for Oldham Athletic before continuing his development with a loan spell at Chorley, giving Vassell his first chance at senior football.
Upon his departure from Boundary Park in 2016 he was snapped up by Walsall on a one-year deal and shortly after was sent out on loan to Chester FC in the National League. He eventually spent two different spells with Chester totalling 31 appearances during the 2017/18 campaign, scoring his first career goal in a 3-2 loss to Barrow.
The following season he joined Gateshead on a permanent deal scoring twice in 35 appearances for the Heed which in turn earned the defender a move to the EFL, as he was snapped up by Port Vale in 2018.
He made his EFL debut against Lincoln City in the EFL Cup and would make 22 appearances in all competitions for the Valiants before heading out to sign for Macclesfield Town the next summer.
With financial trouble at Moss Rose, Vassell followed manager Sol Campbell to Southend United later that season but was unable to sign due to a transfer embargo at the beginning of the season's halt due to COVID-19.
He departed Roots Hall without the opportunity to appear for United and signed for Wrexham on a one-year deal ahead of 2020/21.