Newcastle United Krul began his career at hometown club RAS and later local
Eredivisie club
ADO Den Haag. He joined
Premier League club
Newcastle United in the summer of 2005 on a three-year deal after failing to sign professional terms. ADO demanded a compensation fee and objected to the FIFA Dispute Resolution Chamber (DRC). The DRC denied the claim and ADO took the case to the
Court of Arbitration for Sport (CAS). CAS ruled in February 2007 in favour of ADO, ordering Newcastle to pay €220,000 as compensation for the transfer. Following an injury to Newcastle's first-choice goalkeeper
Shay Given, Krul appeared on the bench as back-up to second-choice
Steve Harper. Krul made his Newcastle debut in the
UEFA Cup on 2 November 2006 against
Palermo. His debut was well-received; he displayed his shot-stopping abilities, saving efforts from
Giuseppe Biava and
David Di Michele and recording a clean sheet in the process. He was injured during the warm-up prior to the second leg tie against
Palermo and then aggravated that injury in the warm-up before a game against
Watford. He required two cartilage operations as a result, keeping him out of action for almost six months. He returned to action in April 2007. On 13 June 2007, he signed a new four-year contract with Newcastle. In the same month, he was part of the Dutch Under-21 squad that won the
European Championships and also qualified for the
2008 Summer Olympics.
Falkirk (loan) On 3 August 2007, Krul joined Scottish side
Falkirk on
loan, originally until 1 January 2008 though it was later extended until the end of the season after a number of impressive performances. The following day he made his debut for Falkirk and kept a clean sheet as the team won 4–0 against
Gretna. Falkirk initially wanted to sign him on a permanent deal but it was refused by Newcastle. In the two games immediately following his debut, he conceded four goals against
Celtic and seven goals against
Rangers at
Ibrox. Krul was sent off for the first time in his professional career on 2 January 2008 after reacting badly to an opponent's challenge. Shortly afterwards, he suffered a dislocated shoulder during a
Scottish Cup defeat against
Aberdeen and missed the rest of the season.
Carlisle United (loan) On 21 November 2008, Krul joined
Carlisle United on a one-month loan from Newcastle to replace
Ben Alnwick, who had rejoined
Tottenham Hotspur. The loan deal was extended for a further month in December with Krul returning to Newcastle in January.
Return to Newcastle in 2012 Krul returned to Newcastle as backup to first choice
Steve Harper. He made his senior league debut on 8 August 2009 in the opening
Football League Championship game of the season away to
West Bromwich Albion, coming on as a half time substitute for the injured Harper. Following this match,
The Guardian called him "an excellent reserve goalkeeper". He later played the full
Football League Cup match against
Huddersfield Town on 26 August 2009, which Newcastle won 4–3. Krul also started the 2–0 League Cup defeat to Peterborough. Against
Swansea City on 28 November, he again came on to replace the injured Steve Harper. On 2 January, he played in the
FA Cup Third Round tie against
Plymouth Argyle, the game ending 0–0. He then played in the replay at
St James' Park on 13 January, a 3–0 victory. Krul started his first league game for Newcastle on 2 May 2010, the last day of the Championship campaign, against
Queens Park Rangers at
Loftus Road and kept a clean sheet. In July 2010, Krul signed a new four-year contract with Newcastle. Krul made his Premier League debut for Newcastle on 18 September 2010 against
Everton at
Goodison Park, coming on as a substitute in the 35th minute for the injured Steve Harper in a match that ended in a 1–0 win for the Magpies. He made his first Premier League start on 26 September against
Stoke City at
St James' Park. He then played against
Manchester City in a 2–1 loss,
Wigan Athletic in a 2–2 draw and in the 2–1 away win to
West Ham United, before starting in his first Tyne-Wear derby, Newcastle winning 5–1, and a 1–0 away win at
Arsenal a week later. Following his good performances,
Alan Pardew gave him more chances. He eventually became first choice and Harper was sent on loan to
Brighton & Hove Albion. He started the 2011–12 season well, keeping clean sheets in the first two matches of the season against
Arsenal and
Sunderland. On 3 December 2011, Krul made his 50th Newcastle appearance against
Chelsea. He saved a
Frank Lampard penalty and made several other impressive saves, although Newcastle went on to lose the game 3–0. On 3 March 2012, Krul signed a new five-year contract at Newcastle United. Krul then went on to play in the away game against Arsenal, which Newcastle lost 2–1. During the match, fellow Dutchman
Robin van Persie accused Krul of wasting time throughout the match and taunted Krul after the match had ended. The row continued into the tunnel and the two players had to be separated. Although he received criticism from Arsenal player
Jack Wilshere, teammate
James Perch defended Krul, believing van Persie "out of order". At the end of the season, Krul received Toon Talk's Newcastle United Player of the Year award. In the summer before the
2012–13 Premier League, Krul was given the number 1 jersey, with
Steve Harper receiving number 37. Krul started the first three matches of the season before suffering an elbow injury whilst on international duty. After seven weeks off, Krul returned to training. Krul made his return in the
Tyne–Wear derby on 21 October 2012, a 1–1 draw. He injured his ankle during a Europa League match in the Round of 32 against Ukrainian side
Metalist Kharkiv which ruled him out for five weeks. In the Tyne–Wear derby on 14 April 2013, Krul suffered a dislocated shoulder on 57th minutes after he landed awkwardly after punching away an
Adam Johnson free-kick. After surgery on his dislocated shoulder, Krul was ruled out for the rest of the 2012–13 season. Ahead of the 2013–14 season, Krul made his first appearance since his ankle injury in a friendly match against
Rangers. In November, Krul made some impressive displays, conceding just two goals and keeping clean sheets against Tottenham, where he made a total of 14 saves during the match), and Chelsea. His impressive displays earned him November's
Premier League Player of the Month. Krul's performance was praised by Newcastle United goalkeeping legend
Pavel Srníček and manager
Alan Pardew. Krul sustained an ankle injury in training before Newcastle's match with
West Ham United and was ruled out for up to six weeks with the injury. Krul returned in his side's 2–0 defeat to
Chelsea.
Return to the Netherlands On 25 August 2016, Krul signed a one-year contract extension at Newcastle United before joining
Ajax on a season-long loan deal to provide him with top-tier first-team football as he continued his recovery from injury. That deal was cut short, Krul only playing six games for the club's reserve side, and, in January 2017, he joined fellow Eredivisie side
AZ Alkmaar on loan for the rest of the season.
Brighton & Hove Albion On 31 August 2017, Krul signed for Premier League club
Brighton & Hove Albion on a season-long loan, reuniting him with former Newcastle manager
Chris Hughton. On 19 September, he made his debut for the club in an EFL Cup third round tie against
AFC Bournemouth. The following day, he signed a permanent deal with Brighton, ending his twelve-year association with Newcastle. At the end of the season, Krul left the club.
Norwich City Krul signed for
Championship club
Norwich City on 24 July 2018 on a two-year contract. He signed a new three-year contract in June 2019. Krul was named
Norwich City's Player of the Season in the club's 2019–20 campaign, making him only the fifth ever different goalkeeper to win the Barry Butler memorial trophy. Krul remained Norwich's starting keeper for the
2020–21 season. He would suffer a hamstring injury in November in a game against Stoke City, being replaced by
Michael McGovern. He proceeded to miss a number of games between then and the end of January, with McGovern or
Daniel Barden deputising, but eventually regained his place as Norwich won the Championship and promotion back to the Premier League. Krul was once again the first choice goalkeeper for the
2021–22 season but Norwich now had
Angus Gunn as an alternative. After a run of poor results, Krul was absent from two games in December with Gunn played instead. Krul would regain his place for the next two games, only to suffer a late injury in a game against Everton. He would be out of the side until March, retaining his place as Norwich were relegated back to the Championship at the first attempt. The
following season would again see Krul start as first choice but his days as Norwich's No.1 were drawing to an end. Following a 3–2 home defeat by
Preston North End, Krul was replaced by Gunn in the starting line-up. He was restored to the side by new manager
David Wagner for his first game in charge, ironically against Preston, with Norwich winning the game 4–0. This was to be short-lived however, and Krul made his final appearance for Norwich two games later, in a 3–0 defeat to
Burnley.
Luton Town On 17 August 2023, Krul signed for newly promoted Premier League club
Luton Town with an undisclosed contract length. On 9 May 2025, the club announced Krul would be released in June when his contract expired. On 23 September 2025, Krul officially announced his retirement from professional football at the age of 37. ==International career==