Marshall played a key role in Scotland's qualification for UEFA Euro 2020, as he made decisive saves in penalty shootouts against Israel and Serbia.

Marshall was born in Glasgow[2] and raised in Riddrie in the east end of the city, where he attended St Andrew's Secondary School.

Marshall was thrust into the limelight soon after these impressive displays for Celtic reserves in March 2004 in a UEFA Cup fourth-round tie against Spanish giants FC Barcelona.

[13] He made his Norwich debut was against Blackpool, but was sidelined for the remainder of the 2006–07 season due to an injury sustained in a FA Cup fourth round tie with Chelsea in February after falling awkwardly on his ankle,[15] and returned to Celtic.

[16][17] He was chosen as the first choice goalkeeper over Finland international Peter Enckelman by manager Dave Jones, making his debut on the opening day of the season in a 4–0 win over Scunthorpe United before conceding his first goal in a 1–1 draw with Blackpool in the following match.

Marshall suffered an injury in a 2–1 loss against Ipswich Town, resulting in Peter Enckelman coming on for the last 45 minutes and two goals being scored.

Marshall retained his first team place for the first two months of the following season, before being dropped for second choice keeper, Tom Heaton after a 2–0 defeat to Ipswich Town.

Marshall didn't see first team football until the beginning of December in a 1–1 draw with Preston North End but only managed to start the next four games before being injured.

[19] Marshall returned the following pre-season as first-choice goalkeeper, starting all the warm-up games under new manager and fellow Scotsman, Malky Mackay.

[20] Marshall made his one hundredth league appearance for Cardiff City on 17 August 2012, the opening day of the 2012–13 season against Huddersfield Town, a game in which he also won man of the match.

[citation needed] In July 2014 manager Ole Gunnar Solskjær claimed that Marshall had been the best keeper in the Premier League of the 2013–14 season.

[26] He received another red card after lashing out at Rotherham United's Matt Derbyshire after he was pulled by the striker, which left Cardiff a goal down, following Vadis Odjidja-Ofoe's penalty.

[29] In August 2016, Cardiff accepted a bid for Marshall worth up to £5 million, including add-ons, from newly promoted Premier League side Hull City.

[42] Some observers expected Marshall to establish himself as the first choice goalkeeper for Scotland, but Craig Gordon and then Allan McGregor were picked more regularly instead.

[42] An injury to McGregor, and Gordon being without a club, appeared to have offered an opportunity for Marshall early in the 2012–13 season, but Matt Gilks played instead.

[49] Marshall won his tenth cap on 19 November 2013 in a friendly away against Norway, keeping a clean sheet and producing several good saves in a 1–0 win for Scotland.

[51] Marshall saved an effort from Eran Zahavi during a penalty shootout against Israel in October 2020, which helped Scotland progress in the Euro 2020 qualifying play-offs.

[56] Following the loss of his first-team place at Derby County, Marshall was dropped from the Scotland squad for World Cup qualifiers in September 2021.