Danish international Thomas Helveg signed for Norwich City on a two year deal on 22nd July 2004. This was a major transfer coup for Nigel Worthington as Helveg is a current Danish international and had played in all of his nation's games at Euro2004. Worthington's role in "charming" Helveg to sign should not be underplayed as he shared his vision for Norwich whilst showing Helveg around the club

The 33-year-old defender, who was released by Italian giants Inter Milan at the end of last season, had a string of English clubs on his trail, with the likes of Everton, Tottenham and Manchester City all believed to be chasing his signature. After spending a couple of days in Norfolk in the company of the Canaries boss, Helveg decided his career would be best served by a move to the Premiership new-boys – and promptly signed on the dotted line.

Worthington stated "I am delighted to get Thomas on a contract at Norwich City. It shows the gradual progress of the club that we can attract a player of his calibre. To have that level of knowledge and experience in the football club is a boost to everyone here.”

However Worthington also owes a big favour to former Norwich favourite Steen Nedergard who helped convince Helveg of the merits of joining Norwich. The two played alongside each other at Danish side Odense, for whom Helveg signed his first professional contract in the late 1980s. He played a few matches in the last part of the 1989 Danish 1st Division winning season, and soon became a regular. He represented Denmark at the 1992 Summer Olympics, playing all three Denmark matches in the tournament. He was put to the task of handling English striker Ian Wright, when Odense played London club Arsenal FC in the 1993-94 Cup Winners' Cup tournament, for which Helveg received praise.

Helveg's international career began when he was loaned out for six months by Odense BK to Italian relegation battlers Udinese from the winter 1993-94. Even though Udinese was relegated in his first season on loan at the club, he received his first call-up to the Denmark national team in 1994. He came on as a substitute in the 14th minute for the injured John Jensen, and Helveg would receive rave reviews for his performance, making him a mainstay in the Denmark squad from day one. Despite their relegation, he was bought by Udinese and was soon to have success in the Udine club. Combined with his international breakthrough with the Denmark team, his first year at Udinese earned him the 1994 Danish Player of the Year award.

Helveg took part in his first major tournament with the Denmark team when he played all three matches at the Euro 1996, which ended unsuccessfully in an early exit in the group stage

Before the 1998 World Cup, Helveg was sold to AC Milan alongside his Udinese teammate Oliver Bierhoff. The transfer deal made Helveg the most expensive Danish player at the time, at the price of £6 million.[4] The shift from Udinese to AC Milan was made easier, when Milan later signed manager Alberto Zaccheroni from the Udinese days. The trio gained success in Milan as they won the Italian championship, Lo Scudetto, in 1998-99. Thomas Helveg played a large role in the success as a starter in almost every game in the season. In the next two seasons he was still first choice, but in the season 2001-02 he began to be challenged severely by the young Italians players like Gennaro Gattuso and Massimo Ambrosini.

In the 2001-02 season he played less than half of Milan's games in Serie A, and following only eight of 34 matches in the 2002-03 season, he moved to Inter Milan - the arch rivals of AC Milan - before the season 2003-04. A funny detail is that Helveg was in fact already owned by Inter, who had bought him in November 2000, and subsequently loaned him to Milan for three and a half seasons. Through his five years at Milan, Helveg had been selected for Denmark in both the Euro 2000 as well as 2002 FIFA World Cup. While the Euro 2000 was no success for neither Denmark nor Helveg, who had an injury keeping him at playing a combined 98 minutes in two games, the 2002 World Cup gave him more time on the pitch. He played full time in the three successful group stage matches, until another injury forced him to leave the pitch in the 7th minute of Denmark's final game before elimination. he was part of the Danish side that reached the last eight of Euro 2004. Helveg joined the Canaries on a Bosman free transfer, and said at the time that he was looking forward to his first taste of Premiership football. “I am very pleased to have signed,” said the man who is renowned for his energetic performances on the right side of defence. “After spending many years in Italy it was a great opportunity to come to England. “I have chosen the right club. It has a great atmosphere and made me feel I was coming home. Now I hope to repay some of the faith that the manager has shown in me. I feel sure that we will succeed together this season".

The versatile star has played most of his football at right-back but has also played on the right side of midfield and in the centre of defence in his time – so his arrival provides Worthington with plenty of options. Thomas made his competitive debut for Norwich on August 14th in the 1-1 Premiership draw with Crystal Palace. Helveg was then appointed captain of the Danish national side following the retirement of Rene Henriksen. He becomes the first Norwich player to captain his country since Martin O'Neill in 1982.

Poor performances and an initial inability to adjust to the pace of the Premiership saw Thomas unable to break into the City first team during the autumn of 2004. With Danish coach Morten Olsen suggesting that Helveg needed regular football if he was to play for his nation and Helveg himself purchasing property in Denmark, the media speculated that he was to return to his homeland and join Odense. Injuries to Damian Francis, Gary Holt and Phi Mulryne at the end of November / beginning of December 2004 saw Worthington affirm that Helveg was going nowhere and he was picked to play in a central midfield role.

Following Norwich's relegation to the Championship in May 2005, Danish side AGF Aarhus claimed that they were in negotiation to sign Helveg. Danish international manager Morton Olsen also encourage Helveg to quit Norwich saying that Championship football was no place for a player of Helveg's pedigree. On 17th June 2005, two national newspapers reported that Helveg was a target for newly promoted West Ham. On 28th June 2005, he was linked with a switch to German Bundesliga outfit Borussia Monchengladbach according to the Daily Mirror. Norwich denounced it as pure speculation but the folllowing weekend, Thomas was in Germany discussing terms and agreeing a transfer with Norwich receiving £135,000. After confirming that an offer had been accepted, City chief executive Neil Doncaster said last night: “Thomas is expected to fly out to Germany on Tuesday to try and agree personal terms and will be undergoing a medical on Wednesday.” This went through successfully.

On 31st January 2007, Thomas returned to Denmark rejoining his first cub Odense, now managed by former City boss Bruce Rioch. Monchengladbach were strugllign at the wrong end of the Bundesliga and Helverg had made just 13 appearances since his transfer from Norwich.

Helveg announced his international retirement at the end of February 2008 having made 108 appearances for Denmark and is his country's second most capped international after Peter Schmeichal.

He retired from playing in December 2010 and is now part of OB's coaching squad. He left this role in June 2013. He was then on the board of FC Roskilde.

In May 2020 he was appointed as assistant coach of Denmark's Under-19s. He left that role in August 2021.

In October 2022, he returned to Odense where he was hired as a 'resource coach'. Helveg's new position included helping with the integration of new players