McManus grew up in Balornock and Bishopbriggs in the north of Glasgow as a boyhood Celtic supporter,[3] and he started his career with Hibernian, making his debut against Stranraer in 1999.
The Dark Blues were struggling in the league, and despite Calum McDonald's goal in a relegation-decider against Livingston, Dundee were demoted to the Scottish First Division.
Financial difficulties at Dundee, resultant from relegation and an earlier spell in administration required them to remove the highest-earners from their wage bill and along with Lee Wilkie, McManus negotiated a release settlement in mid-2006.
McManus signed for Falkirk in August 2006,[5] but after playing a largely peripheral role in the first half of the 2006–07 season, he was released by the Bairns.
[8] He appeared as a substitute in the UEFA Cup against BK Häcken of Sweden on 30 August 2007 and scored the winning goal on 6 October 2007 against Queen of the South.
In March 2008, McManus was approached by MLS side Colorado Rapids and offered a trial while the club were playing friendlies in England.
[12] McManus made his Colorado Rapids debut on 12 April 2008, coming on as a half-time substitute in the game against New England Revolution.
McManus scored his first competitive goal for Derry City on 16 July 2009, in their Europa League Second Qualifying Round first leg match away to Latvian side Skonto FC in a 1–1 draw.
In June 2015, McManus came out of retirement to sign for newly formed Gartcairn Juniors in the SJFA Central District League Second Division but a hamstring injury ended his playing career for a second time in February 2016.