Hamilton Academical's French midfielder Tony Andreu signed for Norwich City on 2nd February 2015 for a fee rumoured to be £1million, following the route to Norfolk taken by Alex Neil. The 26 year old signed a three and a half year deal.

Andreu began his playing career in France and Switzerland with Monaco, Chênois and Stade Nyonnais, making 77 appearances for the latter between 2009 and 2012, scoring 10 goals.

He signed for Scottish club Livingston in June 2012, alongside David Luongo. It was revealed by John Hughes that the director of football John Collins signed the duo, with the help from Collins' French connections by inviting them on trial, which impressed Hughes' management.

He made his debut for Livingston, in the first round of the Scottish Challenge Cup, in a 1–0 loss against Annan Athletic. Andreu scored his first goal in the last minutes, as they beat Falkirk on 2nd September 2013. He made 37 appearances, scoring 10 goals for Livingston

He signed a one-year contract with Scottish Championship side Hamilton Academical on 1st August 2013, having appeared for the club in the Scottish Challenge Cup a few days earlier as a trialist. In April 2014, he was nominated for the 2013–14 PFA Scotland's Player of the Year award, in the Championship section. He was also selected to the 2013–14 Championship PFA Scotland Team of the Year, alongside Hamilton teammates Ziggy Gordon and Ali Crawford. On the last game of the season, Andreu scored a hat-trick, just before half-time, thrashing Greenock Morton. However, the win wouldn't guarantee promotion to Scottish Premiership after Dundee, won at the same day.

He scored the winning goal in the play-off semi-final against Falkirk on 18 May 2014. After losing 2–0 to Hibernian in the first leg of the final, Andreu scored a last minute goal, in a 2–0 win to keep the scoreline alive on aggregate. The match went to a penalty shoot-out which Hamilton would win 4–3 promoting Hamilton to Scottish Premiership. Andreu converted the second penalty in the shoot-out.

At the time of his transfer to Norwich, he was the leading scorer in the Scottish Premiership having scored 12 goals. He had scored a total of 28 goals in 70 appearances for the Accies.

Andreu made his debut for Norwich coming on as a substitute in the 4-0 home win over Blackpool on 7th February 2015. He made a total of six appearances but wasn't involved in the play-offs when Norwich won promotion to the Premier League

Despite a promising pre-season, Andreu was loaned to Rotherham on 1st September 2015 until January 2016.

Andreu only made one first team appearance for Norwich during 2015/16, in the Capital One Cup. The following season, he played in Norwich's 6-1 Capital One Cup win over Coventry and a win by the similar scoreline over Peterborough in the Football League Trophy, scoring a hat-trick on 30th August 2016.

He was loaned to Scottish second tier side Dundee United on 31st August 2016 despite interest from Hamilton and Ross County. "I am delighted with this capture," said United manager Ray McKinnon. "Tony is an excellent player who is a proven goal scorer and he will add real quality and goal threat to our squad." He scored three goals in his first two games for Dundee United.

On 10th August 2018, Andreu left Norwich by mutual consent and signed a two year deal with Mark Robins' Coventry City. Robins said “I am delighted we have managed to get the signing of Tony over the line, it seems like we have been waiting a long time. He is a player that has been on our radar for a while and he is also familiar with some of the playing squad already having played alongside Marc McNulty in Scotland. I believe the supporters will like him. He is a goal-scoring number 10 and a versatile attacking player that can play anywhere along the forward line.” Oxford United were also linked with him.

Andreu returned to Hamilton on 18th January 2019, signing on loan until the end of the season. He made 18 appearances, scoring once.

He was released by Coventry at the end of the 2018/19 season. He had made 18 appearances for Coventry, scoring twice. At the beginning of July 2019, he took up an offer from St Mirrent to join them on pre-season training in Spain. He signed a one year contract with St Mirren on 4th July 2019. St Mirren boss Jim Goodwin backs the former Norwich City and Dundee United man to find his scoring touch: "He's very fit, technically really good, has great timing in the box and hopefully he'll get us a few goals,"

When football stopped due to the Covid-19 pandemic, Andreu and five other St Mirren players were placed on furlough. It was then announced that they would be leaving the club when furlough ended.

On 8th January 2021 he signed for Scottish Premiership bottom side Ross County for the remainder of the 2020/21 season. He was released at the end of the season having made six appearances.

He joined Andorra side UE Sant Julia in February 2022 until the end of the 2021/22 season.