McKeever began his football career with Norwich City as a youth team player. He was eventually released and moved on to Peterborough United with ex-Canaries coach Kit Carson. McKeever became a trainee with the club, but after only 3 appearances he was transferred to Sheffield Wednesday in April 1997 with David Billington for £1,000,000.
McKeever made three appearances in the Premier League and was looking to break into the first team before a foot injury prematurely ended his season. He was subsequently sent on loan to Bristol Rovers and later Reading. During his stint with the Royals he looked like George Best in a 4-0 away victory over Stoke City. However, over the following weeks, Stoke full-back Jason Kavanagh made a full catalogue of Division Two wingers look like Best at his peak.
McKeever made his 6th appearance for Wednesday in an FA Cup tie against Bristol City in December 1999. A year later, Mark was linked with a return to Bristol Rovers after Rovers had supposedly tabled a £100,000 bid for him. But the permanent move did not materialise.
McKeever did move to Bristol Rovers on loan for two months in 2001. In March 2001, the move was made permanent, with McKeever moving south on a free transfer. He spent 2 years with Rovers before being released in May 2003. He then joined Weston-super-Mare in August 2003, for whom he played for a period of three years before signing for Bath City in May 2006.
Bath City sent Mark on loan in January 2008 to Mangotsfield United, but he was soon transferred to fellow Conference South club Weston-super-Mare in March 2008 for his second stint with the club.
On 18 August 2009 he was forced to retire following injury.
McKeever was spotted by agent/talent scout Pauly White in the summer of 2009, and then joined East Worle FC. He won the first medal of his career lifting the Hospital Cup in May 2010 and followed that up with a Weston and District Division 1 winners medal in 2011. At East he was a firm fans favourite and could often be seen mixing with the fans in the bar after the game. McKeever decided to retire from Weston and District football at the top, throwing his future up in the air. Rumours have began circulating that he may follow his old manager to Banwell. Until then McKeever can be seen dominating the 5aside league at priory school on a Thursday night.
He has been capped by the Republic of Ireland at Under-18 level (12 caps) and by their Under-21s (4 caps).