Adkins joined Bangor City as player-manager in 1993, making 95 league appearances and guiding them to consecutive championships before leaving the club in 1996.

[3] Adkins began his managerial career in 1993 as the player-manager of Bangor City in the League of Wales where he won the championship in the 1993–94 and 1994–95 seasons, before departing in February 1996.

[5] As Adkins had been promoted to the manager's seat from the role of club physiotherapist,[6] Scunthorpe supporters chanted, "Who needs Mourinho, we've got our physio!"

[9] He gained his first victory in charge in his third game winning 1–0 at Sheffield Wednesday, with Lee Barnard scoring the only goal.

[10] The good start to his tenure continued and he guided Southampton into the play-off part of the table for the first time in League One on 2 November 2010 after a 4–0 win over Dagenham & Redbridge.

Adkins guided his team into the top two for the first time since being relegated, after a 4–0 win over Exeter City on New Year's Day 2011 and managed a victory against Premier League opposition in Blackpool just one week later, taking his side into the fourth round of the FA Cup.

[20] He then broke a 12-year hoodoo of not winning on the opening day of the league season by beating Leeds United at St Mary's Stadium 3–1 and send them straight into second in the Championship.

[24] They suffered a minor blip in their next game, a 3–2 defeat at Leicester, but bounced back winning 3–1 in the second round of the League Cup at Swindon Town.

Adkins took charge of his first Premier League match as Southampton manager on 19 August 2012, losing 3–2 away to reigning champions Manchester City despite being 2–1 up with 18 minutes of the game remaining.

[32] In October 2012, Adkins disclosed that he recites the Dale Wimbrow poem, The Guy in The Glass to control stress.

[36] On 26 March 2013, Adkins was appointed manager at fellow Premier League club Reading in succession to Brian McDermott, who had been dismissed a fortnight earlier.

On 15 December 2014, Adkins was sacked following his side's 6–1 defeat to Birmingham which left them ten points behind a play-off place in the Championship.

[40] On 7 December 2017, Adkins was appointed as the manager of Championship club Hull City, signing an 18-month contract, following the dismissal of Leonid Slutsky.

[47] On 8 June 2019, Adkins confirmed his decision not to renew his expiring contract, stating that his and the club's futures were "not aligned".

[49] On 21 October 2021, Adkins left Charlton Athletic following a poor start to the 2021–22 season which saw the club slip to its lowest ever league position.

[50] On 7 May 2023, Adkins returned to Tranmere Rovers as technical director, mentor and advisor to manager Ian Dawes.