Lambert was born in Glasgow, but moved to Linwood, Renfrewshire when he was a child. He played for Linwood Rangers Boys’ Club before entering the professional game with St Mirren in 1985. With St Mirren, the 17-year-old Lambert won his first senior winner’s medal courtesy of the 1987 Scottish Cup Final; Saints beat favourites and that season’s UEFA Cup Finalists Dundee United, in what turned out to be the last time the Scottish Cup was won by a team composed entirely of Scottish players. Due to his age, manager Alex Smith had to send the youngster home early from the alcohol-fuelled celebrations. Lambert played with St Mirren for eight years, experiencing relegation from the top tier in 1992.

Lambert played in the Champions League final as a defensive midfielder, quelling the influence of Juve’s French playmaker Zinedine Zidane. Lambert’s cross also set up Karl-Heinz Riedle’s opening goal as Dortmund won 3–1. His contribution has since been lauded as a Man of the Match performance. He became the first British person to win the European Cup with a non-UK team, and the first British person to win the tournament since its reformation as the Champions League in 1992.

Lambert represented Scotland at every age group level. During Lambert’s international career, he was involved in a memorable Under-21 game against Germany. The young Scots drew 1–1 in Bochum in the 1992 UEFA European Under-21 Football Championship quarter-finals. In the return leg at Pittodrie, Germany were two up after 40 minutes before Duncan Ferguson set up Ray McKinnon to pull one back before half-time. Germany scored a third on the hour mark to seemingly put the tie out of reach. However, on 68 minutes, Gerry Creaney headed past Stefan Klos before Lambert himself equalised ten minutes later. Alex Rae scored two minutes from time to clinch the game 4–3.

In September 1993, Lambert was signed by Tommy McLean for Motherwell for a fee of £250,000 in a transfer move that saw Jimmy Gardner move to St Mirren. The club finished in 3rd place at the end of the 1993–94 season in the Scottish Premier League.

As a full Scotland international, Lambert won 40 caps, scoring one goal. In the latter part of his international career, he captained the side 15 times. His international debut came whilst at Motherwell and awarded by Craig Brown in the 1995 Kirin Cup against host country, Japan. Lambert played a second game in the tournament three days later against Ecuador.

Lambert won the club’s Supporters Player of the Year, while he was also shortlisted for the SPFA Players’ Players award in 1996. He left Motherwell at the end of the 1995–96 season under freedom of contract, as new rules were implemented following the Bosman ruling.

Whilst at Dortmund and during the 1998 FIFA World Cup qualification campaign Lambert started to appear as a regular. After missing the opening game of the campaign against Austria, Lambert appeared as a 46th-minute substitute in the 2–0 win in Latvia in October 1996. He was also in the starting line-up for the next fixture against Estonia in Tallinn four days later, but a scheduling dispute meant the home team did not adhere to a quickly-rearranged afternoon kick-off time, and the match was abandoned at kick-off with no caps awarded to the Scotland players (the fixture was re-arranged for the following February, but Lambert was an unused substitute). He was again a substitute in the next qualifier which was played, coming on in the 46th minute of a 1–0 home win against Sweden. For his next cap, he was promoted to the starting line-up for a 2–0 home victory in the qualifier against Austria. Lambert’s only defeat of the campaign was the 2–1 reversal in Gothenburg against Sweden before two wins against Belarus and a second 2–0 win against Latvia clinched qualification.

It was announced the Champions League group stage game on 5 November 1997 against Parma, his 23rd in European club competitions, would be Lambert’s last before he returned to Scotland. He was given a rousing send off by the Dortmund fans, and reciprocated with a banner he had prepared thanking the Dortmund fans for their support. Lambert scored one domestic league goal during his time with Dortmund, against Bayer Leverkusen.

In November 1997, after just over a year playing in the Bundesliga, appearing in 44 matches, he was signed by Wim Jansen for Celtic for a fee in the region of £2 million. Lambert made his debut on 8 November 1997 when he came on as a substitute in a league match at Ibrox against Rangers. Three weeks later on 30 November 1997, Lambert picked up his first winner’s medal as a Celtic player when he came on as a late substitute in Celtic’s 3–0 win over Dundee United in the Scottish League Cup Final. Thereafter, Lambert became a regular in the starting line-up and scored from 25 yards in a 2–0 win over Rangers at Parkhead in the New Year game. Lambert went on to help the Scottish giants win the championship that season, their first in ten years, halting Rangers’ run of nine consecutive titles which had previously equalled the total achieved by Celtic in the Jock Stein era.

Lambert was part of the Scotland side that won away against Germany in April 1999 with the goal scored by Don Hutchison. Lambert and Scotland qualified for a play-off place in the 2000 UEFA European Football Championship qualifying campaign, but Lambert missed the play-offs against England due to suffering an injury in the Old Firm game played the weekend before. Craig Brown cited Lambert’s absence as crucial to England’s progression at Scotland’s expense, since he intended to deploy Lambert directly against Paul Scholes, scorer of both England goals.

During his seven seasons with Celtic, he won four Scottish Premier League titles, two Scottish Cups, two Scottish League Cups and was Scottish Football Writer’s Player of the Year (also nominated for the SPFA Players’ Player award) in 2002. Lambert captained the side that reached the 2003 UEFA Cup Final in Seville; his team were drawing 2–2 after 90 minutes but after having a man sent off in extra time, conceded a third and decisive goal to José Mourinho’s Porto.

He scored his only goal for Scotland on 7 September 2002, in a Euro 2004 qualifier against the Faroe Islands, which ended in a 2–2 draw. Lambert was awarded Man of the Match in a 1–1 draw with Germany in June 2003. His final cap came in a 2–1 defeat against Germany in September 2003. The match was played in Dortmund, where he had achieved great success during his club career.

After studying for football coaching qualifications in 2005, Lambert landed his first managerial job with Livingston on 1 June 2005, assisted by Norrie McWhirter. Although he had not intended to play for his new club, Lambert registered as a player in late August 2005 to cover for any injury shortages. His tenure ended in February 2006 when he resigned after only winning two league games since starting the job.

Lambert was appointed manager of English team Wycombe Wanderers on 30 June 2006. He led Wycombe to the League Cup semi-finals after defeating Premier League sides Fulham and Charlton Athletic. The semi-final tie, against Premier League champions Chelsea, saw Wycombe hold Chelsea to a 1–1 draw at Adams Park before losing the away leg. This was the first time in over 30 years a fourth tier team had reached that stage of the League Cup. Lambert resigned as Wycombe manager on 20 May 2008 following the club’s elimination from the League Two play-offs by Stockport County.

On 9 October 2008, he was appointed as manager of League One team Colchester United to succeed Geraint Williams, before winning his first game 2–1 at Stockport County. Despite occasionally threatening to flirt with the League One play-offs, the U’s eventually finished mid-table in Lambert’s first season. On 8 August 2009, he began the 2009–10 season with an opening day 7–1 win over Norwich City. Lambert left the Essex club for Norwich shortly afterwards.

On 15 November 2009, he was inducted into the Scottish Football Hall of Fame.

Lambert became the new manager of Norwich City on 18 August 2009, replacing Bryan Gunn, who was dismissed by the club shortly after the 7–1 defeat to Colchester. He led Norwich to the League 1 title and promotion to the Championship in April 2010.

On 1 June 2010, he signed an improved contract with Norwich after it was confirmed Colchester United were entitled to £425,000 in compensation, in addition to Norwich City being fined £75,000, with a further £125,000 suspended for two years.

In January 2011, Norwich refused to allow Burnley permission to try to secure Lambert as their new manager, following the dismissal of Brian Laws. The Norwich statement read, in part, “The club will fight tooth and nail to retain the services of Paul Lambert and his team during this critical period of the season and whilst they remain employed under a long-term contract”. On 2 May 2011, Lambert and Norwich secured promotion to the Premier League after a win over Portsmouth, taking the second automatic spot with one game to spare. Lambert signed a new contract to extend his stay with the Norfolk club. He was inducted into the Norwich City Hall of Fame in March 2012.

Following Norwich’s survival in the Premier League in the 2011–12 season, Lambert offered his resignation on 31 May 2012, but the club declined it.

On 2 June 2012, Lambert was confirmed as the new manager of Aston Villa replacing Alex McLeish, who was dismissed two weeks earlier. Lambert’s first competitive match as Aston Villa manager came on the opening day of the Premier League season on 18 August 2012, a 1–0 defeat to newly promoted West Ham United at Upton Park. His first Premier League win came on 15 September 2012, a 2–0 victory against Swansea City at Villa Park. He was handed a one-match touchline ban on 21 November 2012 for comments relating to a penalty decision in Villa’s defeat to Manchester City. On his first return to Carrow Road, Lambert received a mixed reception from the Norwich fans on 11 December 2012, in a League Cup quarter-final which his Villa team won 4–1.

On 23 December 2012, Villa were defeated 8–0 against Chelsea at Stamford Bridge, the club’s heaviest ever defeat in top-flight football. This was followed by consecutive home defeats, with Villa losing 4–0 to Tottenham Hotspur and 3–0 to Wigan Athletic, leading to increased pressure on Lambert’s position. On 22 January 2013, Villa played Bradford City in the second leg of the League Cup semi-final at Villa Park, having lost the first round tie 3–1 at Valley Parade. The final score on the night was a 2–1 win for Villa, leaving an aggregate score of 4–3 to Bradford.

Lambert’s Aston Villa side began the season brightly, with a 3–1 win over Arsenal at Emirates Stadium on 17 August. Towards the end of 2013, the performances worsened greatly, especially home form, and Lambert was criticised by many fans and pundits for putting out a counter-attacking side with no plan B. Possession stats were biased towards the opposition in many games, including at home to Swansea; Villa had less than 30 percent of possession in a game which ended 1–1. In January 2014, Lambert made headlines by claiming that “many Premier League clubs could do without the distraction of the FA Cup if they were being honest.” Aston Villa subsequently lost 2–1 at home to Sheffield United, a team two divisions below them, marking the fourth consecutive year that Lambert has been eliminated from the FA Cup by lower league opposition. Lambert subsequently defended his comments, claiming they were “taken out of context.”

On 11 February 2015, Villa announced they had parted company with Lambert after a 2–0 loss at Hull, leaving the club 18th in the Premier League table. His departure also meant that the top flight had no Scottish manager, for the first time in 30 years. On 14 February, Tim Sherwood was announced as his successor.

Lambert was appointed manager of Championship club Blackburn Rovers on 15 November 2015 on a two-and-a-half-year deal, with the club in 16th place following the dismissal of Gary Bowyer. Lambert secured Championship safety for Blackburn with a 2–2 draw against Bristol City on 23 April 2016. Blackburn ended the season with two consecutive wins, finishing in 15th place. The club confirmed that Lambert had activated a release clause in his contract, and would step down as manager after their last match of the 2015–16 season on 7 May 2016.

On 5 November 2016, Lambert was appointed head coach of Championship club Wolverhampton Wanderers, taking over with the team in 19th place. The team achieved an upset victory in the fourth round of the 2016–17 FA Cup, winning 2–1 against Liverpool at Anfield. The team finished the 2016–17 EFL Championship season in 15th place.

On 30 May 2017 the club announced that they and Lambert had “agreed to part company following a football review”.

On 15 January 2018, Lambert was appointed manager of Premier League club Stoke City, signing a two-and-a-half-year contract with the Potters, and officially took up post the following day. He joined Stoke with the club in the relegation zone, having dismissed previous manager Mark Hughes due to a poor run of form. Lambert was unable to prevent Stoke’s continued decline and relegation from the Premier League, and he left the club by mutual agreement in May 2018.

On 27 October 2018, Lambert was appointed as the manager of Championship club Ipswich Town, making him the first ever manager to manage both Ipswich and Norwich. He joined his new team on a contract until the summer of 2021, with the side bottom of the Championship. On 10 February 2019, Lambert was sent off following a touchline bust-up with the opposing team staff during a game against former club and rivals Norwich City. He was subsequently fined and handed a two match touchline ban by the FA. Despite this, Lambert stated he didn’t regret his actions that led to his dismissal.

Lambert was ultimately unable to keep Ipswich in the division, as relegation was confirmed on 13 April 2019. This ended Ipswich’s 17-year stay in the Championship, and resulting in them playing third-tier football for the first time since 1957.

Despite the team’s relegation, Lambert remained in charge and led Ipswich to the top of the League One table during the first month of the 2019–20 season, winning 14 league points out of possible 18 during August. He won the EFL League One Manager of the Month award for August 2019. On 1 January 2020, Lambert signed a new 5-year contract with the club until 2025. Despite a strong start, Lambert failed to achieve promotion with the team finishing in 11th after the league was determined on a points-per-game basis due to the COVID-19 pandemic.

On 27 October 2020, he was given a one-match touchline ban for directing foul and abusive language towards referee Kevin Johnson. He was also fined £1,000.