|Full name||Niklas Lars Roger Gudmundsson|
|Date of birth||29 February 1972|
|Place of birth||Trönninge, Sweden|
|Height||1.80 m (5 ft 11 in)|
|Playing position||Midfielder, forward|
|1995–1996||→ Blackburn Rovers (loan)||4||(0)|
|1997||→ Ipswich Town (loan)||10||(3)|
|* Senior club appearances and goals counted for the domestic league only.
Gudmundsson started his youth career at hometown club Trönninge IF before joining the youth rankings of Halmstads BK in 1986. His first senior appearance came in the last round of the 1988 Swedish football Division 1 against IK Oddevold, also securing promotion to the Allsvenskan. He became a first team regular in 1990 and won the 1994–95 Svenska Cupen. Gudmundsson also had a trial at Norwich City, but was not signed.
During the 1995–96 UEFA Cup Winners' Cup, Gudmundsson scored twice in a 3-0 against Parma, only to see a 4-0 defeat in the away leg that knocked Halmstad out of the competition. After finishing in the 3rd place at the 1995 Allsvenskan, he moved to Premier League side Blackburn Rovers first on a loan until March 1996, when he was purchased for £1 million.
He made his debut for the 1994–95 FA Premier League champions in a 3-0 win against Sheffield Wednesday on 20 January 1996. He made a total of four appearances for the Rovers while on loan before getting injured and also had two appearances in the 1996-97 season, all of them coming from the bench. In March 1997, he was loaned to Ipswich Town, scoring 3 goals in 10 Football League First Division games. Although he impressed at the club, they were unable to afford his transfer fee and he returned to Blackburn Rovers.
After returning to Blackburn, he was out of the plans of the new coach Roy Hodgson and was transferred to Malmö FF with the English club receiving Anders Andersson in the deal. He played at Malmö FF until the end of 2000 and was targeted by Norwegian club Bryne FK after being relegated in the 1999 Allsvenskan, but no deal was completed.
In 2001, he moved to IF Elfsborg, winning the 2000-01 Svenska Cupen. He played only 3 league matches in 2002 due to a knee injury. In 2003, he signed for Ängelholms FF, playing for the club until 2007.
Gudmundsson played for all the national team ranks, amassing a total of 26 goals in 81 appearances combinining youth, olympic and senior matches.
He was part a member of the Swedish squad at 1991 FIFA World Youth Championship playing in the 3 matches at the tournament and part of the team that qualified to the 1992 UEFA European Under-21 Championship, playing four qualification matches plus both legs of the tournament final. He made his senior international debut in 1991 in a friendly match against Poland.
In 1992, he played at both legs of the 1992 UEFA European Under-21 Championship final. Gudmundsson played in 3 of the 4 matches that Sweden played in the 1992 Olympic football tournament, all as a substitute. Although Sweden did not qualify to the 1994 edition, Gudmundsson scored 5 times during the qualification.
Gudmundsson returned to the Sweden national football team in 1995 for a UEFA Euro 1996 qualifying match against Hungary. He also appeared in the three Umbro Cup matches and friendlies against the United States and Scotland in the same year.