Andy McDonald was born in Acklam, Middlesbrough in North Yorkshire.
McDonald was educated at a number of local schools, including St. Francis Primary School, St. Edward's Primary School and St. George's Secondary School (which later became Trinity Catholic College, Middlesbrough). He attended St. Mary's Sixth Form College before studying for a law degree at Leeds Polytechnic.
He worked as a lawyer for over a quarter of a century and rose to be Senior Serious Injury Solicitor at the Middlesbrough office of Thompsons Solicitors and to lead the firm's Serious Injury Unit for the Cumbria, Humberside, North East, and Yorkshire areas. He was also the Thompson's Head of Military Claims for members of the British Armed Forces. Whilst working for the firm, McDonald acted as a special adviser to the House of Commons Defence Select Committee for its 2003 report on Armed Forces Pensions and Compensation. He has also served as both Chair and as Secretary of the Association of Personal Injury Lawyers' Military Special Interest Group and was a founder member of The Royal British Legion's Solicitors Group.
McDonald has been involved in various good causes in the Middlesbrough area. He was a governor of Abingdon Primary School for fifteen years until 2010 and became a governor of Middlesbrough College in 2012. He has also been chair of two local charities, the Davison Trust, which works with children with special needs, and the Teesside branch of Headway, which works with people with brain injuries.
McDonald was active in local politics in Middlesbrough for many years. He served as councillor for Westbourne ward from 1995 to 1999. At the time of his selection as a parliamentary candidate, he was chairman of Middlesbrough Labour Party Local Government Committee. Labour shortlisted McDonald as a potential candidate for the Middlesbrough South and East Cleveland constituency in the 2010 United Kingdom general election. However, Tom Blenkinsop was the eventual choice.
McDonald became a parliamentarian when he won the Middlesbrough by-election held on 29 November 2012, retaining the seat for Labour following the death of Sir Stuart Bell. McDonald increased the party's share of the vote to 60.5% though his majority was reduced by 500 to 8,211.
In February 2013, McDonald announced his appointment as Parliamentary Private Secretary (PPS) to Emily Thornberry MP, Shadow Attorney General.
Since his election to Parliament, McDonald has campaigned on a number of issues including opposition to the "Bedroom Tax" (part of the Welfare Reform Act 2012) and the privatisation of the East Coast Main Line. Following the Ed Miliband's Shadow Cabinet reshuffle in October 2013, it was announced that McDonald would become Parliamentary Private Secretary to Chuka Umunna MP in his role as Shadow Secretary of State for Business, Innovation and Skills.
In January 2016, McDonald was appointed to Jeremy Corbyn's Shadow Ministry to replace Jonathan Reynolds who resigned as Shadow Minister for Rail in protest after Corbyn sacked Pat McFadden.
in June 2016, McDonald was appointed Shadow Transport Secretary as part of the Labour Party's post-Brexit reshuffle.