Born in Carmunnock, the son of a butcher was raised in a small village outside East Kilbride, and educated at Rutherglen Academy.
McColl left school at 16 to take up an engineering apprenticeship with Weir Pumps of Cathcart, Glasgow. After gaining City & Guilds certificates at lower and higher level, he gained a BSc Degree in Technology and Business Studies at Strathclyde University. He returned to Weir Pumps in 1978, studying for the next three years for an MBA.
McColl joined Diamond Power Speciality Ltd in 1981, an engineering company supplying equipment to the power industry worldwide; during his tenure he studied part time for a Master's degree in International Accounting and Finance. Head hunted by Coopers & Lybrand, in 1985 he became a consultant, working with companies in financial difficulties that needed guidance. In 1986 he left Coopers to become a self-employed "company doctor", during which he made money through two successful turnarounds.
In 1992 McColl bought 29.9% of the family-owned engineering company Clyde Blowers plc for £1million, which was then losing money on a turnover of £4million, but had a full listing on the London Stock Exchange. After taking it private company and increasing his holding to 70% in 2001, over the following five years Clyde Blowers bought six of eight major competitors, and now have a 55% global market share of their original core business. In May 2007, Clyde Blowers bought Weir Pumps from the Weir Group plc, the same company McColl started his career at. In September 2008, McColl led a team which enabled Clyde Blowers to acquire the entire Fluid & Power Division of Fortune 500 multi-industry company Textron, in a deal worth over $1 billion. Clyde Blowers presently consists of 85 companies in 27 different countries, employing 5,000 people around the world, with an annual turnover in excess of £1.35 billion.
McColl was appointed Officer of the Order of the British Empire (OBE) in the 2001 Queen's Birthday Honours. McColl won an "Alumnus of the Year" award from Strathclyde University in 1998, was awarded an honorary doctorate by Napier University in 2003, and an honorary doctorate by Glasgow University in 2007. McColl won the Entrepreneurial Exchange 'Entrepreneur of the Year Award' for 1999/2000, and the Ernst & Young "Master Entrepreneur of the Year Award" for 2001. In July 2005, McColl was awarded The Prince Philip Medal 2005 'Certificate of Achievement' for an outstanding contribution to the engineering industry. In May 2006, McColl was presented with a Scottish International Business Achievement award from The Princess Royal.
McColl and his wife Shona are now resident in Monaco. They also have a home outside Glasgow, and McColl is a keen car enthusiast for both modern and classic cars.
McColl was a supporter of the Scottish Government's policy of independence for Scotland, but in early 2015 changed his viewpoint stating that "the decision's been made" following the 2014 referendum though he supports the idea of further tax devolution. His is a member of the Scottish Government's Scottish Council of Economic Advisers, and spends much of his spare time working on a Glasgow based welfare-to-work programme.
On 28 March 2010, it was reported in the Sunday Herald that, after discussions with the Rangers Supporters Trust about a takeover designed to make the football club a supporter-owned entity, McColl was believed to be backing their bid for Rangers. McColl later told BBC Scotland that he had no interest in any personal financial involvement but was providing finance advice to the Rangers Supporters' Trust. McColl was part of a consortium, led by former Rangers manager Walter Smith, that attempted to buy Rangers from liquidators BDO for £6million.