A nephew of Scotland scrum half Roy Laidlaw, he joined Edinburgh in the summer of 2006. His first-team opportunities were limited at first behind Scotland scrum-half Mike Blair, but in 2010 he signed a new two-year contract.
His earlier representative rugby included games for Borders under-16 and under-18 as well as Scotland under-18. After stints with the Scotland sevens and under-21 sides, he made his full Scotland debut against New Zealand at Murrayfield in November 2010. In January 2011, he was called up to Scotland's Six Nations squad and, although he did not get any game time, he was retained in Andy Robinson's 40-man squad ahead of the World Cup. He captained Scotland A to wins over the Ireland Wolfhounds and Italy A in early 2011, and then skippered Edinburgh in the Magners League.
He became a regular part of the Scotland team during the 2012 Six Nations, following Dan Parks' sudden retirement after the first round of the tournament. He took on the kicking duties, and in his first start against Wales he scored all of Scotland's 13 points, including a try. He remained at fly-half throughout the rest of 2012 at both international and club level, and captained Edinburgh to a semi-final appearance in that year's Heineken Cup.
The 2013 Six Nations saw Ruaridh Jackson recalled to the national side, so Laidlaw was shifted back to scrum-half while still taking Scotland's kicks. He was second-leading scorer of the season with 61 points, behind Wales' Leigh Halfpenny. He was left out of the 2013 Lions squad, instead heading to the South African Quadrangular Tournament with Scotland. He kicked a last-minute conversion against Italy to salvage something from an underwhelming tournament, giving Scotland a 30–29 victory. He continued to captain Edinburgh throughout the 2013–14 season, missing out on a place in the Amlin Challenge Cup on points difference.