He was manager of Cardiff City between June 2011 and December 2013, achieving promotion to the Premier League in 2013 but was dismissed after a dispute with club owner Vincent Tan.

Born in Bellshill,[1] Mackay began his career in his native Scotland, coming through the youth ranks of Queen's Park,[2][3] before joining Celtic in the summer of 1993.

[4] He made 46 appearances in five years with the Glasgow club, and in September 1998 moved to England, joining Norwich City for a fee of £350,000 after a one-game loan spell.

Mackay was involved in some excellent defensive displays as well as scoring some vital goals, including one against fierce rivals Luton Town at Kenilworth Road in a 2–1 victory.

[10] During his sixth and final season at Norwich, at the age of 32, Mackay became the oldest man to make his debut for Scotland in 37 years.

[15] Mackay signed a three-year contract as Cardiff City manager on 17 June 2011, with Watford receiving an undisclosed fee in compensation.

[18] He guided Cardiff to their first ever League Cup final, following wins over Oxford United, Huddersfield Town, Leicester City, Burnley, Blackburn Rovers and Crystal Palace in earlier rounds.

[19][20] The week before the League Cup final, Mackay signed a three-and-a-half-year contract extension, tying him to the club until June 2016.

[23] Following the success of his first season in Wales, Mackay was reportedly one of the candidates to replace Paul Lambert at Premier League side Norwich City.

[26] During the 2013–14 season, Mackay came under criticism from club owner Vincent Tan concerning his signings, transfer budgets, results and style of play.

[29] Mackay was appointed manager of Wigan Athletic on 19 November 2014, despite fan opposition,[30] after the Championship side had dismissed Uwe Rösler.

[31] The appointment was criticised by the Kick It Out campaign, who said that the club had disregarded the ongoing FA investigation into text messages sent by Mackay.

[42] The anti-racism campaign group Kick It Out made comments that were supportive of Mackay, pointing out that he had since received equality and diversity training from the (English) FA.

[48] Mackay was sacked by County on 15 November 2023, with the team on a nine-game winless run and sitting in 11th place in the Premiership table.

[49] The news came on the same day as the sacking of head coach Nick Montgomery, with the club saying that Mackay would lead the process for appointing his replacement.

[50][51] Cardiff questioned the fees paid to agents and lawyers relating to transfer deals made while Mackay and Moody worked for the club.

[51] Via a statement published by the LMA, Mackay apologised for writing two messages that he admitted were disrespectful of other cultures, but denied stating anything of a homophobic or sexist nature.