England Under 21 goalkeeper Andy Marshall was the first choice keeper at Carrow Road having displaced Bryan Gunn. A youth team product, Andy came to prominence in the 1994/95 season when Gunn was injured for half the season. Loan spells at Gillingham and Bournemouth during the 1996/97 season gave him more first team experience and he managed to displace Gunn as first choice custodian of the City goal.

In July 2000, Andy was named as a potential successor to Ipswich keeper Richard Wright who had been transfer-listed as he had not agreed a new contract with the Premiership newboys. However it was highly unlikely that Norwich would sell to their arch-rivals. In October 2000, Andy was linked with Aston Villa and Celtic who were hoping to exploit Andy's disillusionment with Norwich's investment in catering facilities rather than the first team squad. In February 2001,Andy was linked with a move to Filbert Street where he would join up with Darren Eadie and Ade Akinbiyi as Leicester players with a Norwich background.

Andy was voted Norwich City Player of the Year for 2000/01, edging out Iwan Roberts by a mere 30votes. Andy was linked, along with Darel Russell with a move to Ipswich on May 3rd as George Burley was allegedly scouting the 2 Canaries in order to strengthen his successful Tractor Boys. Whether Andy Marshall would be happy deputising his good friend Richard Wright is another matter. Derby have also been linked, possibly in conjunction with rumours that their Estonian keeper Mart Poom was headed for Old Trafford. Despite reports linking him with Wolves, by 25th May Bolton appeared clear favourites to sign Marshall especially if they gained promotion into Division One. He would be equivalent in ability to Bolton's current on-loan keeper Matt Clarke for whom Bradford would require a fee if the move became permanent. Jussi Jaskelainen would be Marshall's deputy with third choice keeper Steve Banks possibly heading to Norwich. Marshall confirmed that Bolton were one of four clubs that he was in regular contact with but Bolton and Marshall failed to come to agreement.

Andy joined local rivals Ipswich on July 2nd 2001 on a Bosman free transfer. He was the first player to make this journey since John Deehan in the mid 80s. Andy replaced Richard Wright who made a £6million move to Arsenal. Andy stated that the chance of competing in the Premiership and in Europe was what led him to Ipswich whilst George Burley the Ipswich manager had been impressed with Marshall in action and when training with Malcolm Webster

In December 2002, the Sunday People reported that Arsenal had been watching Marshall and his young Ipswich teammate Darren Ambrose. With Arsenal needing a keeper following injuries to Stuart Taylor and Rami Shaaban, and Ipswich seriously in debt, it would suggest that there may be a grain of truth in this report. However Marshall's form for Ipswich had not been great and he had lost his place to loan signing Paul Gerrard. An injury to Gerrard enabled Marshall to regain the Number One shirt and his form helped Ipswich climb the table and finish just outside the play-offs at the end of 2002/03. His form allegedly gained the attention of Division One champions Portsmouth who were going to bid to bring him to Fratton Park, according to the media.

In a shock development in mid May 2003, Joe Royle announced that Marshall was available on a free transfer. Royle wanted to bring in an experienced keeper who was more reliable than Marshall who later admitted his form had been inconsistent as he found it hard to settle in Suffolk. Another benefit for Ipswich would be cutting Marshall's wages from the wage bill as he is one of their highest earners. If Marshall does not find himself a new club, he would return to Ipswich for pre-season training in July as he still has another year on his contract. Clubs rumoured to be interested in him included Portsmouth and Stoke City whose manager Tony Pulis knows Andy from his loan period at Gillingham. On 23rd July 2003, the media linked Marshall with a move to Reading but the Berkshire side dismissed this. After Premiership newboys Wolves conceded 5 at Blackburn and 4 at home to Charlton in their first two games of the 2003/04 season, it was speculated that Wolves manager David Jones would bring Marshall to Wolves although Jones has also brought former Newcastle keeper Pavel Srnicek in on trial. There were then rumours that Marshall would be brought to Bramall Lane to replace the injured Paddy Kenny but Sheffield United instead switched their attention to Everton's Paul Gerrard.

Later in September 2003, Plymouth made enquiries to take Andy on loan but he rebuffed these stating that he wanted to stay in Division One or the Premiership. Luton also made an approach which he was willing to consider as they are a local side. On 11th November 2003, PlanetFootball.com jumped the gun in reporting that Andy had joined Wimbledon on a month's loan following injuries to Paul Heald and Steve Banks, and Lee Worgan's suspension after his sending off. However the BBC reported that Wolves had also made a bid for Andy's services. Wolves were successful in their bid and Andy joined them on a month's loan commencing 17th November 2003.

He returned to Portman Road in January 2004 only to depart on loan to Millwall on 27th January 2004, ironically as cover for Tony Warner who had been linked with a move to Wolves. This loan was made permanent on 25th March 2004 (Transfer Deadline Day). Andy's season finished on FA Cup Final Day when he kept goal for Millwall at the Millenium Stadium against Manchester United. Although Millwall lost 3-0, Andy had a good game producing some good saves and hopes that this will lead to a new contract.

The new season saw Millwall use loan signing Graham Stack of Arsenal as first-choice keeper and on October 22nd 2004, Andy announced that he would be seeking a transfer if he did not get first team football. He instead stayed with the club until the end of the 2005/6 season but following their relegation to League One, the Lions announced that they would be allowing Marshall to leave. Indeed he did leave, joining Coventry City on a free transfer at the end of June 2006.

In March 2009, Coventry boss Chris Coleman announced that Marshall would be leaving Coventry in the summer. To help him prepare for the future, Marshall has begun his UEFA "B" coaching course.

After a successful trial with QPR during July 2009, the London side offered Marshall a one year deal at the beginning of August 2009 to act as cover for Radek Cerny Instead he signed for Martin O'Neill's Aston Villa on 12th August 2009 on a one year deal. Marshall is expected to join Brad Guzan in providing cover for current number one Brad Friedel.

In November 2009, it was rumoured that Marshall would rejoin QPR, initially on loan ahead of a permanent transfer in January 2010. Andy was released by Villa in June 2010 - he had not played a first team game for them.

In July 2010, Andy trained with Colchester playing 45 minutes for the Us in their 3-0 victory over Maldon & Tiptree in a pre-season friendly on Saturday 17th July. After training with Charlton, Andy re-signed for Villa on 3rd September 2010. He became their second choice keeper following Brad Guzan's loan to Hull. Marshall signed a new one year contract with Villa on 28th March 2011.

Marshall was told by Villa on 23rd May 2013 that his contract would not be renewed when it expired at the end of June 2013. On 8th August 2013, Marshall re-joined Millwall on a short term contract after David Forde was ruled out for about a month with a knee injury.

At the end of January 2014, Marshall announced his retirement from the professional game.

He also helps run the Sells Goalkeeping Academy which has seven centres across Britain providing elite goalkeeping coaching for youngsters aged eight to eighteen.

Marshall returned to Villa as goalkeeping coach in the 2014/15 season and was made caretaker manager, along with Scott Marshall, on 11th February 2015 following the sacking of Paul Lambert. They managed just one game, a 2-1 win over Leicester in the FA Cup as Villa appointed Tim Sherwood as their new manager.

In June 2018, Marshall joined Charlton as goalkeeping coach and at the end of his first season at The Valley, Charlton were promoted to the Championship via a play-off final win on 26th May 2019 against Sunderland.

He followed former Charlton boss Lee Bowyer to Birmingham City in June 2021. He departed St Andrews on 2nd July 2022 following the sacking of Bowyer.

In July 2022 he was appointed as Millwall's new goalkeeping coach