Brolin’s first professional match was for Näsvikens IK in 1984 at the age of 14 against Kilafors, and he went on to make 36 appearances for the fourth division club. GIF Sundsvall, spotted Brolin and offered him a contract in which he could continue his education while developing his career. In 1986 Brolin enrolled at Fotbollsgymnasiet, the football academy in Sundsvall. He was subsequently signed by GIF Sundsvall, making his first team debut in 1987 against IF Elfsborg.

Brolin was signed by Italian club Parma in 1990, just after the club had been promoted back to Serie A. He quickly formed an effective partnership at Parma with Alessandro Melli: The two together scored 20 goals, 13 from Melli and 7 from Brolin. Parma finished in joint fifth-place in their first season back in Serie A. It was the first time that the team qualified for Europe in their history.

Eighteen days later, Brolin was lining up against Wales at the Råsunda Stadion, and five minutes after Dean Saunders had given the visitors the lead, Brolin announced his arrival on the international stage with two goals in six minutes to give Sweden a 2–1 lead. Sweden won 4–2 on the night, and Brolin went on to score another two in the following match with Finland a month later, which Sweden won 6–0. Subsequently, Brolin was picked to lead the Swedish attack in the 1990 World Cup in Italy. Sweden failed to win any of their matches at that tournament, however, but after scoring against Brazil, Brolin was soon signed by Parma for £1.2 million (out of a possible 12 buyers), and also won his first Guldbollen as Sweden’s footballer of the year.

On 16 November 1994 at the Råsunda Stadion in Stockholm, Brolin had broken his foot in a qualifier for UEFA Euro 1996. At the time of his injury, Parma were two points clear at the top of the 1994–95 Serie A league table. By the time he returned on 23 April 1995, however, Parma were eight points behind leaders and eventual champions Juventus. With Gianfranco Zola missing, Brolin was given his first full start after his injury on 7 May 1995, a week after he resumed playing for Sweden. His first start in nearly six months came against Genoa, and Parma needed a victory to keep the pressure on runaway leaders Juventus. Brolin lasted 62 minutes before he was substituted for Stefano Fiore as Parma drew 0–0 and slipped seven points behind in the title race. Brolin struggled the rest of the season to find his form and fitness, but nonetheless continued to make appearances. On the last matchday of the season, against Napoli, Brolin was sent off for the first time in his career in the 23rd minute.

Brolin scored three goals for Sweden in the 1994 World Cup as the nation finished third in the competition. Brolin’s performances earned him a place in the competition’s World Cup All Star Team. In the quarter-final against Romania, he scored one of his most famous goals: When Sweden were awarded a free-kick, everyone expected Stefan Schwarz to shoot. Instead, Schwarz jumped over the ball and Håkan Mild passed the ball past the wall to Brolin, who managed to score. He received his second Guldbollen award in 1994.

On 16 November 1994, at the Råsunda Stadion in Stockholm, Brolin broke his foot in a qualifier for Euro 1996. On 7 May 1995, a week after he had returned from injury, Brolin played for Sweden against Iceland, and scored a penalty but was unable to help his team to a much needed victory in their qualifying campaign.

Brolin turned down three Italian clubs before moving to Leeds United on 7 November 1995. On 17 November, he signed a two-and-a-half-year contract. Coach Howard Wilkinson saw Brolin as the perfect foil for the club’s top scorer Tony Yeboah.

On 1 April 1996, Brolin had to apologize to Howard Wilkinson after an April Fool’s Day prank backfired. He had told Swedish television that he was going to play out the season on loan to former club IFK Norrköping as a joke but the statement was then picked up by international media and re-reported as fact. He returned on 3 April, however, and played in the matches against Southampton, Arsenal and Nottingham Forest. He played his last match of the season at Stamford Bridge on 14 April, setting up Gary McAllister’s goal in the 4–1 defeat to Chelsea, but was dropped for the following match against Manchester United. On 1 May, it was announced by the club that Brolin had returned home to Sweden undergo surgery to remove scar tissue from his troublesome ankle, and was not fit for Leeds’ last two league matches, or indeed at all generally. Brolin’s future at Leeds, however, was already in doubt.

In the middle of 1996, Brolin went searching for a club and was granted three extra days by Wilkinson to find a new club, however no serious interest was forthcoming. On 19 August 1996, Leeds announced that Brolin was on the transfer market and were prepared to sell him for nearly £2 million less than the £4.5 million paid for him just a year earlier. Leeds manager Wilkinson had fined Brolin a week’s wages around £12,000 for not turning up to pre-season training and announced he was seeking guidance from the Professional Footballers’ Association on the legality of withholding Brolin’s wages, and told the press that he would rather have any player in his team than Brolin. Leeds stopped his wages when he refused to show up for pre-season training and reportedly saved £72,000 by the time Brolin had joined FC Zürich on loan, where he received the minimum wage of £800-a-week for a player in the Natonalliga A.

Brolin joined the Swiss club on 20 August 1996 and played three matches for Zürich in the Nationalliga A and one Swiss Cup match against lowly Uzwil, which Zürich won 10–0. Brolin wanted to stay at the club until their mid-season winter break in December to get back to full fitness, but Leeds’ new coach George Graham wanted him back at Elland Road and refused to allow him to play for the club against St. Gallen on 9 October, after his loan spell ended on 30 September. Graham was quoted as saying, “We have heard nothing from Tomas Brolin. We have not even got a telephone number for him. All our correspondence with him has been done through his agent, Lars Peterson.” Leeds gave Brolin an ultimatum to return to the club on 6 November or face legal action.

On 16 April 1996, Brolin was then dropped by Swedish coach Tommy Svensson for a friendly against Northern Ireland in Belfast, and was quoted, “Brolin is not at 100 percent at the moment and it is difficult to say when he will be.” Brolin told Swedish news agency TT that it was the best for him, and the national side: “Right now I need to recover in order to get to the capacity needed to add something to the national team.”

Leeds urged Brolin to return to Yorkshire and have tests on his damaged ankle to clarify the extent of the injury, fearing Brolin would be forced to retire, and wanted him to seek a second opinion from a leading orthopaedic surgeon. Then, on 24 December, Brolin paid £500,000 of his own money to fund his loan move back to Parma until the end of the season. Brolin trained with the club but did not return to first team action until 23 February 1997 as a second-half substitute in a 2–0 win over Lazio. He also made substitute appearances against Cagliari (3–2), Perugia (2–1), Inter (1–0) and Fiorentina (0–1), all in March 1997.

On 16 June 1997, Brolin’s loan deal with Parma expired. Under the terms of the agreement, he was obligated to return to Elland Road within 72 hours. Brolin, however, was axed by coach George Graham for the club’s pre-season tour of Sweden. Brolin was forced to find another club on loan or play for the reserves.

After the two failed loan deals, Brolin continued to train and play in the reserves. On 6 October, he was fined £90,000 after missing a match to attend his father’s 50th birthday as well as criticizing George Graham in the media. The player threatened to take the club to a Premier League tribunal. On 28 October 1997, club officials, Brolin, and Brolin’s representatives decided to terminate Brolin’s contract for a reported £140,000.

On 16 November 1997, Steve Coppell, the manager of struggling Crystal Palace, offered Brolin a two-week trial. Palace had been playing a friendly in Sweden, and Coppell was hoping to finalize the two-week trial while he was there. At the time, Brolin was training with Hammarby IF in Stockholm.

The trial began on 5 January 1998. With a player shortage, Brolin was asked by Coppell to play for the club in a league match. Brolin was registered as a player for the club and allocated the number 12 jersey. He played in the home league match against Everton on 10 January, and netted a ball in the 72nd minute only to see the referee rule it out for offside. The club lost 3–1 but Brolin, whose trial ended on 16 January, was handed a contract until the end of the season.

Brolin went on to play 12 more times for Palace, mostly as a striker due to the London club’s shortage of players up-front. On 13 March 1998, the club lost to Chelsea 6–2. Crystal Palace had been procured by Mark Goldberg who decided Steve Coppell should step down as manager and player Attilio Lombardo would take over as player-manager. Despite it being widely reported that Brolin was to be his assistant coach, Palace chairman Goldberg insisted that the fluent Italian and English speaking Brolin was merely Lombardo’s interpreter.

Brolin’s last competitive game came in the 3–0 defeat to Manchester United on 27 April 1998. He was substituted for Jamie Fullarton after 68 minutes. Brolin was unable to recapture his form or fitness failing to score in 15 appearances. Palace were relegated from the Premier League and on 14 May 1998, he was released from the London club and returned to Sweden to think about his prospects.

On 12 August 1998, the player announced his retirement from the game and made his last appearance on 29 August 1998 in the last 15 minutes for Hudiksvalls A.B.K. against Kiruna FF, as a goalkeeper.

In 2001, a long-time girlfriend, Susan Hardenborg, gave birth to Brolin’s first child, a boy named Sebastian. The couple had split before the birth of the child, but remain on good terms. During this time he was married to the former Miss Sweden and TV presenter Annika Duckmark until they got divorced in 2006.

Although he recovered from his ankle injury, Brolin never regained his pre-injury level of fitness. He made 19 Premier League appearances for Leeds, scoring four goals. He is widely regarded by Leeds fans as one of the club’s worst ever players, and in 2003, a poll by BBC Sport saw him voted by the club’s fans as the club’s worst player in living memory, with the editor joking that Brolin had given almost all of his £4.5 million fee back to the local catering industry with “dedicated munching”.

Brolin has been an active World Series of Poker player since 2006. Playing in the 2007 World Series of Poker and the 2006 Football & Poker Legends Cup organized by PartyPoker.com. He has also competed regularly in the PokerStars.com European Poker Tour and cashed twice – once in the Season 4 Prague event where he came 23rd and again in the EPT Grand Final later that season in Monte Carlo where he came 38th out of an 842-strong field.

In 2012, Brolin claimed in Swedish magazine Offside that his poor performance in the game against Liverpool that led to his being dropped had been a protest against Wilkinson playing him out of position on the wing, leaving him “to run up and down the right like an idiot” as opposed to the centrally lying playmaker role he believed that he had been signed for.