After retiring from playing, he went into management with the Ajax youth team and as assistant to Bert van Marwijk with the Dutch national team. In December 2010, he took over as manager of Ajax and went on the win the Eredivisie title in his first season. In 2013, De Boer received the Rinus Michels Award for manager of the year in the Netherlands after leading Ajax to their third successive Eredivisie title. A year later, he became the first manager to win four consecutive Eredivisie titles.
He is the twin brother of Ronald de Boer, with whom he was a teammate at Ajax, Barcelona, Rangers, Al Rayyan, Al-Shamal and the Netherlands national team.
De Boer began his career as a left back at Ajax before switching to centre back, a position he made his own for many years in the national team. He won both the 1991–92 UEFA Cup and 1994–95 UEFA Champions League while at Ajax, in addition to five Eredivisie titles and two KNVB Cups. However, after signing a six-year contract extension with Ajax for the 1998–99 season, he and his twin brother Ronald took successful legal action to have it voided. Ajax had a verbal agreement that if a lucrative offer for one brother came by, he would be released provided the other stayed. However, Ajax apparently backed down on that agreement after floating the club on the stock market and pledging to shareholders that it would hold both of the De Boers and build around them a team to recapture the UEFA Champions League.
In January 1999, Frank and Ronald de Boer signed for FC Barcelona for £22 million, joining their former Ajax manager Louis van Gaal at the Camp Nou. After winning the 1998–99 La Ligatitle, they were unable to repeat their earlier triumphs. In 2000, Van Gaal was sacked by Barcelona and Frank suffered the ignominy of testing positive for the banned substance nandrolone a year later. He was suspended but he was reinstated after a successful appeal.
He briefly moved to Galatasaray in the summer of 2003 before joining his brother at Rangers in January 2004. He made a total of 17 appearances for Rangers, scoring two goals. The De Boer brothers left Rangers after UEFA Euro 2004 to play the rest of their football careers in Qatar with Al-Rayyan. De Boer announced his retirement from football in April 2006.
Having represented his national team 112 times, he was the most capped player in the history of the Netherlands national team, until Edwin van der Sar surpassed him. De Boer made his debut for the Netherlands in September 1990 against Italy. De Boer also played for the Netherlands in the 1994 and 1998FIFA World Cups, and the 1992, 2000 and 2004UEFA European Championships. He is well-remembered for the arching 60-yard pass which allowed Dennis Bergkamp to score the last-minute goal that knocked out Argentina in the quarter-finals of the 1998 World Cup. During Euro 2000, hosted in his home country and Belgium, De Boer reached another semi-final with the Dutch team. De Boer missed an important penalty kick in the penalty shootout in the semi-finals, which led to defeat against Italy. He also missed a penalty during the match. He ended his international career after an injury forced him to be replaced in a quarter-final game with Sweden at Euro 2004. The injury ruled him out from the semi-final match against Portugal, which the Netherlands lost 2–1.
In 2007, De Boer took up a coaching role at his former club Ajax where he was in charge of the club's youth sector. During the 2010 World Cup, he was the assistant of the Netherlands national football team, with retired player Phillip Cocu. On 6 December 2010, after the resignation of Martin Jol, De Boer was appointed caretaker manager of Ajax until the winter break. His first game in charge was a UEFA Champions League match against A.C. Milan at the San Siro, a game they won 2–0 through goals from Demy de Zeeuw and Toby Alderweireld. He then went on to help Ajax become champions of the Eredivisie for the 2010–11 season in a 3–1 home victory over FC Twente, the champions of the previous year, on the final matchday. Making the first year of his professional coaching career a golden one. "I couldn't have wished for a more beautiful birthday present," said De Boer, as the club's 30th championship was won on his 41st birthday.
In two and a half years at the helm of Ajax, De Boer has already won three championships, making eight in total (when including the five that he won as a player). According to reports, De Boer was offered the chance to interview for the Liverpool job but turned it down to remain with Ajax. "I am honoured by the request [from Liverpool] but I have only just started with Ajax," he said. In 2013, De Boer received the Rinus Michels Award for manager of the year in the Netherlands after leading Ajax to their third successive Eredivisie title.
On 27 April 2014, De Boer won his fourth successive Eredivisie title with Ajax, the first manager ever to achieve this in the Dutch league. Moreover, it is the first time Ajax has ever won four successive titles. De Boer has now won nine championships with Ajax, another record. Johan Cruijff, Sjaak Swart and Jack Reynolds all won eight championships with Ajax.
^"Dutch defender Frank de Boer plays a sixty-metre pass, which finds a gap on the right side of the Argentina defence. At an unpromising angle, the ball drops from its high arc towards Holland's player of the age, Dennis Bergkamp, ..." Winner, David (2002). Brilliant orange: the neurotic genius of Dutch soccer. Overlook Press. ISBN978-1-58567-258-5.
^Ginanjar, Asep; Asep Ginanjar; Agung Harsya. 100+ Fakta Unik Piala Dunia. Penerbit Serambi. ISBN978-979-024-212-8.|access-date= requires |url= (help)