The 2006 Heineken Cup Final was a rugby union match played at the Millennium Stadium in Cardiff, Wales, on 20 May 2006, to determine the winners of the 2005–06 Heineken Cup, European rugby's premier club competition. The match was contested by Irish province Munster and French side Biarritz. It was the 11th Heineken Cup final overall and the third final appearance for Munster (their first since 2002, when they lost 15–9 to Leicester Tigers), while Biarritz were competing in their first final. It was the second time the Millennium Stadium had hosted the Heineken Cup final, the other being in 2002, and the fourth to take place in Cardiff, including finals played at the old Cardiff Arms Park.

Each team needed to progress through the group stage and two knockout rounds to reach the final, playing nine matches in total. Biarritz and Munster each won their respective groups to qualify for the quarter-finals. Biarritz then beat Sale Sharks in the quarter-finals and Bath in the semis, while Munster beat Perpignan in their quarter-final and fellow Irish province Leinster in their semi. Chris White, representing the Rugby Football Union, was the referee for the match, which was played under a closed roof in front of 74,534 spectators.

Biarritz scored first through a Sireli Bobo try, converted by Dimitri Yachvili, in the 2nd minute. Munster scored a penalty goal through Ronan O'Gara in the 7th minute and took the lead 10 minutes later, when Trevor Halstead scored a try that was converted by O'Gara. Yachvili scored a penalty for Biarritz to level the match at 10–10, before Munster scored their second try courtesy of Peter Stringer (again converted by O'Gara) to give them a 17–10 half-time lead. In the second half, O'Gara extended Munster's lead to 10 points with his second penalty of the game, but Yachvili reduced Biarritz's deficit to one point with three unanswered penalties in the space of 22 minutes; however, another penalty for O'Gara in the 73rd minute pushed Munster further back in front. There were no further scores, giving Munster a 23–19 win and their first Heineken Cup title.

The Heineken Cup, the premier club competition of European rugby, was established by the Five Nations Committee in 1995 as a new competition for professional rugby clubs across Europe. Its first 10 seasons were dominated by English and French clubs, who won 9 of the 10 titles, Ulster the sole Irish victors in 1999. In 2005–06, the participating teams were drawn from the English Premiership, the Irish/Scottish/Welsh Celtic League, the Italian Super 10 and the French Top 14 based on their domestic performance the previous season. In the 10 previous Heineken Cup finals, the only previous meeting between an Irish side and a French one was in Ulster's 21–6 win over Colomiers. This was Munster's third final in the competition and their first since 2002, when they lost 15–9 to Leicester Tigers. They had also lost 9–8 to another English side, Northampton Saints, in the 2000 final. Meanwhile, Biarritz were appearing in their first Heineken Cup final and were thus also aiming to win their first Heineken Cup. The two teams had met each other twice before in the competition; Munster had won their first encounter in the competition 38–29 in the quarter-finals of the 2000–01 Heineken Cup, while Biarritz won the other match at the same stage of the 2004–05 tournament. Approximately 15,000 Munster fans watched the match on a giant screen in O'Connell Street, Limerick.

The 2005–06 Heineken Cup featured 24 teams from England, Wales, Scotland, Ireland, France and Italy, who were drawn into six groups of four teams each. Teams were awarded four points for a win and two for a draw, with bonuses awarded to teams scoring four of more tries, and/or losing by seven or fewer points. The winners of each of the six groups as well as the two highest-placed runners-up qualified for the quarter-finals. The knockout stage then progressed as a single-elimination tournament.

Biarritz were drawn into Pool 4 with Italian club Benetton Treviso, English side Saracens and Ulster from Ireland. Their campaign started with a 22–10 loss away to Saracens at Vicarage Road on 23 October 2005, but they responded with a bonus-point victory at home to Ulster at Parc des Sports Aguiléra six days later, winning 33–19 to go top of the pool. Two more bonus-point wins in back-to-back games against Benetton followed in December, winning 34–7 on matchday 3 with the bonus point secured shortly after half-time, before scoring six tries in the reverse fixture at Stadio Comunale di Monigo six days later as they won 38–24. On matchday 5, Biarritz faced Ulster at Ravenhill; Biarritz won 24–8 to end Ulster's run of 14 matches without defeat at home. In the final pool match at home to Saracens eight days later, Biarritz against scored six tries to win 43–13 and guarantee a place in the quarter-finals as pool winners.

Due to Heineken Cup regulations that knockout matches had to be played at a neutral venue, Biarritz's quarter-final against Sale Sharks on 2 April was played at the Anoeta Stadium in San Sebastián. A penalty goal by Dimitri Yachvili gave Biarritz the lead midway through the first half. Charlie Hodgson equalised for Sale five minutes later, only for Yachvili to restore Biarritz's lead moments later. A try from Sireli Bobo gave the home side an 11–3 lead at half-time. Hodgson scored a second penalty for Sale with five minutes left to play, but Biarritz held on to win 11–6 and qualify for the semi-finals. As Biarritz were the higher-seeded team in the semi-finals, their match against Bath was again played at the Anoeta but this time in wet conditions. Yachvili scored two penalties in the first 16 minutes, before Chris Malone pulled one back for Bath. The pair then scored another penalty each to give Biarritz a 9–6 lead at the end of the first half, and they increased their advantage to nine points in the first five minutes of the second half via another Yachvili penalty and a drop goal from Damien Traille. Malone kicked a third penalty for Bath in the 64th minute, but Yachvili restored Bath's lead two minutes from the end, giving them an 18–9 win and a place in their first Heineken Cup final.

Munster were drawn in Pool 1 with French side Castres, Newport Gwent Dragons from Wales and English club Sale Sharks. Like Biarritz, Munster began away from home against English opposition; at Edgeley Park in Stockport on 21 October 2005, Munster led 13–9 after 47 minutes, but second-half tries from Sililo Martens and Jason Robinson, and two penalties from Charlie Hodgson gave Sale a 27–13 win. A week later, Munster recorded a bonus-point 42–16 win at home to Castres at Thomond Park in Limerick to maintain their 21-match unbeaten run there in the Heineken Cup. Munster picked up another win in the first of their back-to-back games against the Dragons at Rodney Parade on 10 December, although they missed out on the try-scoring bonus point in the 24–8 victory. In the return game at Thomond Park the following week, the Dragons had an 18–17 lead going into the final 15 minutes, but two penalties from Ronan O'Gara and a try by Jerry Flannery in the final minute gave Munster a 30–18 win, although they again missed out on the bonus point. However, that was not a problem in the game against Castres at Stade Pierre-Antoine on 13 January 2006, when they scored seven tries, including two each for Paul O'Connell and Tomás O'Leary, to win 46–9. Munster went into their final match at home to Sale five points behind the visitors in the pool, needing to record a bonus-point victory and also deny Sale a losing bonus point to top the pool and guarantee qualification for the quarter-finals. Victory was practically assured by half-time, as Munster took a 24–9 lead through tries from Anthony Foley, Ian Dowling and Barry Murphy, but the second half looked to be scoreless until two minutes past the regulation 80, when David Wallace scored the fourth try they needed to overtake Sale and win both the game and the pool.