Born in Birmingham, McKeown began his career aged 15 with Coventry City and Walsall youth teams, but was unable to establish himself and departed two years later.

McKeown was then loaned to Conference North side Boston United during the 2010–11 season where he made a total of 14 clean sheets in 18 games.

A sixth-month stint at Dutch semi-professional outfit RKSV Leonidas had led to a trial with Eredivisie side Willem II, however, his previous managers at Boston signed him for Grimsby Town; he was ever present in the starting XI and five years on helped Grimsby to win promotion out of the National League in 2015–16 and 2021–22.

McKeown started his career with Coventry City as an Under-10 striker in their youth system, he went on trial in goal and spent two years in their Under-11s before being released.

[8] On 9 February 2008, McKeown made his first appearance for Peterborough United in League Two, coming on as a 76th-minute substitute for the injured Joe Lewis who was stretchered off following a nasty aerial collision.

[24] However, despite his remarkable record of clean sheets and fantastic form whilst on loan at Boston Peterborough United came to an agreement with James that he should seek pastures new.

[25] McKeown spent a week at Lincoln City on trial[26] and a one-off appearance for Boston United in the FA Trophy due to their keeper Dan Haystead being cup tied,[27] he then signed for Dutch Rotterdam based semi-professional side RKSV Leonidas in the Hoofdklasse league.

[46] He also played in the 2015 Conference Premier play-off final against Bristol Rovers at Wembley on 17 May 2015; following a 1–1 draw after extra time, Grimsby lost 5–3 in a penalty shoot-out.

[48] As training was in full swing for the 2015–16 season, McKeown was admitted to hospital on 18 July 2015 and diagnosed as suffering with viral meningitis.

[58] McKeown made his League Two debut with the club on 6 August 2016 in the opening game of the 2016–17 season in Grimsby's 2–0 home victory against Morecambe.

[59] After losing the number 1 spot to Manchester United loanee Dean Henderson on 28 January 2017 McKeown confirmed he had handed in his transfer request.

[69] In the absence of Danny Collins through injury,[70] McKeown was made team captain for his first time in his professional career on 22 December 2018 in a 4–0 win over Notts County.

[73] During the 2021–22 campaign, McKeown lost his regular place in the team to Max Crocombe, with the club ending up returning to the Football League at the first time of asking.

[76] McKeown had made 432 league appearances and 505 in total for Grimsby over eleven seasons with the Mariners and was regarded as a club legend by the local media upon his departure.

[87] In April 2019, McKeown expressed an interest to represent San Marino and had hoped to be called up for their Euro 2020 qualifying games.