Wallace started his career Heart of Midlothian, making his debut in 2005 at age seventeen, and joined Rangers seven years later.

[5] Wallace made his debut in the 2004–05 season[5] against Kilmarnock in the Scottish Cup on 5 February 2005 and became a regular member of the first team squad although he found it hard to dislodge Takis Fyssas from the left back position.

In the summer of 2006 fellow Scottish Premier League club Dundee United had a loan bid for Wallace rejected.

[8] Wallace was made Hearts vice-captain at the start of the 2010–11 season,[9] however, a month later while representing Scotland in a Euro 2012 qualifier against Liechtenstein, he suffered a cruciate ligament injury following a late challenge by Martin Stocklasa.

[11] Wallace made his Rangers debut in the Champions League qualifier on 26 July 2011, in a 1–0 defeat, at the hands of Swedish side Malmo.

[23] Wallace opened the 2015–16 season campaign by scoring a brace in Rangers' 3–1 home victory over St Mirren on 7 August 2015.

[24] Wallace was officially appointed captain on a permanent basis prior to Rangers' 5–1 win over Alloa Athletic at Recreation Park on 16 August 2015.

The match ended in a 3–2 win for opponents Hibernian,[26] whose supporters staged a pitch invasion at the final whistle; some Rangers players were confronted in the process of leaving the field, with Wallace a particular target due to his association with their Edinburgh derby rivals Hearts, and he appeared to be struck by at least one person during the disturbance.

[30] Wallace missed a 2016–17 Scottish League Cup match against Peterhead on 9 August 2016, which ended a run of consecutive competitive appearances at 69 that had begun in February 2015.

[33] Following a 4–0 defeat by Celtic in the 2017–18 Scottish Cup semi-finals, Wallace and teammate Kenny Miller were suspended by Rangers due to an alleged altercation with manager Graeme Murty.

[36] In early September, he was not included in the Rangers squad for the 2018–19 UEFA Europa League group stage;[37] two days later, it was announced that he and Kenny Miller had won an appeal at a SPFL tribunal against the disciplinary action taken against them five months earlier, with the expectation they would make a financial claim against the club for the fines imposed.

[46] Alongside Hearts team-mate Calum Elliot, Wallace was an integral part of the Scotland under-19 team that reached the final of the 2006 European Championships, where they lost 2–1 to Spain.

[10] Following Rangers' demotion to the Scottish Third Division, doubt was cast on Wallace's future international career by Craig Levein.

[50] In August 2013, Rangers teammate David Templeton expressed his surprise at the omission of Wallace from the Scotland squad for the special challenge match with England.

[51] Manager Ally McCoist urged Wallace to use being overlooked for the international at Wembley as motivation to push into future Scotland squads.

[56] Wallace played in a 2018 World Cup qualifier against England at Wembley in November 2016, due to injuries to Robertson and Kieran Tierney.