Laudrup made his international debut for the Denmark under-17 team in July 1984, and played six matches for the team until October that year. From October 1985 to August 1987, he played 12 matches and scored 6 goals for the under-19 team. He also represented the under-21s in five games from June 1987 to November 1988. He was called up for the senior Denmark national team by coach Sepp Piontek in April 1987 as a replacement for his brother Michael, but did not receive his debut.

Laudrup was included in the senior Danish “Olympic national team” of under-21 coach Richard Møller Nielsen, and took part in three qualification matches for the 1988 Summer Olympics. He made his debut on 18 November 1987, at age 18, in a 0–1 defeat to West Germany, with Bjarne Goldbæk also debuting in that match. Laudrup scored his first national team goal in his third game, a 4–0 win against Greece on 20 April 1988. He was then included as a part of coach Piontek’s selection ahead of the UEFA Euro 1988. He came on as a substitute in a friendly match against Austria in April 1988, but broke his collarbone just before the final Euro 1988 squad was named.

Laudrup was recalled to the senior national team in February 1989, and became a mainstay in the team under new national team coach Richard Møller Nielsen. He scored three goals in four matches as Denmark narrowly missed qualification for the 1990 FIFA World Cup. During the dispute with Brøndby over his transfer fee, it was discussed whether the Danish Football Union should ban Laudrup from the national team. Following three matches in the qualification campaign for the Euro 1992, Laudrup opted to quit the national team in November 1990 alongside his brother Michael and Jan Bartram, as he lacked respect for coach Nielsen.

Laudrup began his senior career with Brøndby in Denmark. At Brøndby, he competed with later Danish internationals Claus Nielsen and Bent Christensen for a place in the starting line-up, and formed a great partnership with Nielsen. He won the 1987 and 1988 Danish First Division with the club. Halfway through the 1989 season, Laudrup’s contract with Brøndby expired, and he agreed to join German club Bayer Uerdingen. The transfer fee was thought to be around DKK 8 million, the partition of which Brøndby and Brian’s father and agent Finn Laudrup disagreed about. The Danish Football Union ruled in favor of Brøndby’s claims of around DKK 3.9 million, but the Laudrups paid around DKK 3.3 million, and insisted on not paying the remainder. The case was eventually settled in March 1990.

Laudrup’s great performances in the Bundesliga and for Denmark attracted Bayern Munich for his signature, who purchased him for a DM6 million transfer fee in May 1990, making him the most expensive Bundesliga player at the time. In his first season, Laudrup scored 9 goals in 33 games as the club finished in second place. Laudrup was also part of the Bayern squad that reached the semi-final of the 1990–91 European Cup.

Laudrup was a consistent performer in his first five matches of the 1991–92 season but suffered a cruciate ligament injury in his right knee in August 1991. Laudrup watched from the stands as the team collapsed in a disastrous season. In December 1991, Laudrup said new Bayern executives Franz Beckenbauer and Karl-Heinz Rummenigge were creating chaos in the team through their public criticism of the younger Bayern players. He returned to the team in February 1992 and played the last 15 matches of the season as Bayern finished in tenth position. Despite the injury-hit season, Laudrup still finished the 1991–92 season being named Danish Player of the Year again for the second time, and finished fifth in the FIFA World Player of the year poll.

Laudrup returned to the national team under coach Nielsen in April 1992. In 1992, Laudrup travelled with the Danish national team to Euro 1992 in Sweden, and in a strictly defensive strategy, Laudrup was one of the few attacking players. Though he did not score a single goal in the competition, his skill and speed was an important part of the Danish team that went on to win the tournament, and Laudrup was voted a shared fifth in the 1992 FIFA World Player of the Year poll, with fellow Dane Peter Schmeichel, though he had the edge over Schmeichel in the domestic polls, where Laudrup won his second Danish Player of the Year award in 1992.

Laudrup was loaned to Milan for the 1993–94 season, which only saw him play a handful of matches throughout the season due to a squad rotation system at the club, and also because of the three foreigner rule at the time. The world class team of Milan at the time had seven foreigners, including Laudrup, Marcel Desailly, Jean-Pierre Papin, Dejan Savićević and Marco van Basten, which meant Laudrup was not always used. It was also manager Fabio Capello’s very strict system where he preferred to play more defensive type players rather than the direct play preferred by Laudrup. However, Capello’s defensive system proved to work at the end of the season, as Milan won the Scudetto only scoring 36 goals in 34 matches. Laudrup played seven European matches for the 1993–94 UEFA Champions League-winning Milan side. Despite being on contract with Fiorentina until the summer of 1996, Laudrup stated in December 1993 he did not want to return to the club.

In July 1994, Laudrup was offered an escape route from Italy when he was approached by Walter Smith of Rangers. Rangers at that time were an ambitious club and had money to spend to try to seek European glory. This attracted Laudrup, and he signed for a £2.3 million transfer fee.

He made an immediate impact at Rangers. On the opening league fixture of the season against Motherwell in August 1994, it was from his precise cross that Mark Hateley headed the opening goal. In the second half with only a few minutes remaining, he provided another assist with a long run from the half-way line before passing to Duncan Ferguson, who then scored Rangers’ second goal to clinch a 2–1 win. He scored his first goal for the club later that same month, in a Scottish League Cup tie against Falkirk. Although Scottish football was more physical than what he was previously used to, he excelled in the free role given to him by manager Walter Smith. Laudrup turned down an offer from Barcelona five months after signing for Rangers. He finished the season with 10 goals in 33 League games, in addition to a number of assists, as Rangers won their seventh consecutive Championship. As recognition of his fine performances, Laudrup won both the Scottish Football Writers and Scottish PFA player of the year awards. His performances for Rangers and Denmark also resuted in his winning his third Danish Player of the Year award.

Laudrup missed a run of nine League games in the early part of season 1995–96 due to an injury sustained in international duty. He returned against Celtic in November 1995 and scored Rangers’ first goal in a 3–3 draw at Ibrox. He was also now playing alongside Paul Gascoigne, and the pair were instrumental in Rangers winning their eight league championship. Laudrup also made a big impact in the latter stages of the Scottish Cup that season. He scored the winning goal in the semi-final against Celtic, playing a one-two with Gordon Durie, before taking control of the ball on his chest and chipping it over the Celtic keeper. In the final against Hearts, Rangers won 5–1. Durie scored a hat-trick, the first-ever Rangers player to do so in the final, but it was Laudrup who won the Man of the Match award, having provided assists for all three of Durie’s goals, and scoring the other two himself. The game has since become known as the Laudrup Final.

Laudrup was a vital part of the Danish team that won the Confederations Cup in 1995. He scored a remarkable individual goal in the 2–0 win over Saudi Arabia which saw him beat three defenders before slotting it into the net from a wide angle. The goal is rated by FIFA as one of the greatest goals ever scored in the history of the competition. Denmark defeated Argentina in the final 2–0, with Laudrup providing an excellent dribble down the wing to assist in the second goal. Laudrup won the Golden Ball award naming him the best player of the tournament.

His third season at Rangers, 1996–97, saw another cup final goal, this time in a 4–3 win over Hearts in the 1996 Scottish League Cup Final. The season’s most notable concern was Rangers bid to equal Celtic’s record of nine consecutive league titles. With Rangers hampered by a series of niggling injuries to their main strikers, a greater burden for goalscoring was placed on Laudrup. He responded by scoring 16 goals in 33 league games, including the only goal against Celtic in a win in November 1996, and a headed goal in a 1–0 win in May 1997 away at Dundee United which clinched the league title and the club’s bid for nine-in-a-row. His performances saw him win the Scottish Football Writers’ award once again. His great performances for Rangers and Denmark also made him win his fourth Danish player of the year.

Laudrup was linked with a £5 million move to Ajax Amsterdam in the summer of 1997, but was persuaded to stay with Rangers for one more season to help their bid for a tenth successive league title. However, despite a bright start, the season ended up an anti-climax, with Laudrup failing to match the form of previous seasons. Rangers finished runners-up in the league behind Celtic, and ended the season trophy-less after losing to Hearts in the 1998 Scottish Cup Final. Laudrup left the club shortly afterwards. He later described his time at Rangers as “the four best years of my career”.

Laudrup moved back to Denmark in the spring of 1999 for a brief spell with Copenhagen. Playing for the main rivals of former club Brøndby, he was unceremoniously booed by the home fans when he revisited Brøndby Stadium in March 1999, and was also harassed by fans from other Danish clubs.

On 7 September 2010, he announced that he had lymphoma and was undergoing treatment. Three months after the start of the treatment, he was told there were no signs of the disease.

Laudrup has been praised by several players, managers, pundits, and footballing figures for his footballing ability, including Charlie Nicholas, Roland Wohlfarth, Charlie Nicholas, Ally McCoist, and Andy Goram. Franz Beckenbauer described Laudrup as “a world class player,” a view shared by Andreas Brehme, who described him as a “player of the highest quality class.” Paul Gascoigne instead dubbed him an “amazing player.” Laudrup’s older brother, Michael, likened Brian’s playing style to his own, and even believed his younger brother to be superior to himself. His former manager Horst Wohlers named him as the best player he had ever coached, and as the top footballer in the Bundesliga during their time together at Bayer Uerdingen. In December 2013, Graeme Le Saux named Luís Figo and Brian Laudrup as his toughest opponents ever. Walter Smith’s view of Laudrup was more critical however, lauding his ability but also lamenting his mentality, which he believed limited him as a player, commenting: “Brian Laudrup is as good a player as I have ever worked with, but he frustrated me. He had the capability of being up there with the greatest players of all time. There was just that little bit in him mentally that stopped him from being right at the very top. Make no mistake, he was a fantastic player for us, but he could have elevated himself into a position where he was one of the best in the world.”