The 51-year-old Frank will replace Ange Postecoglou, who was fired last week despite leading Tottenham to their first trophy in 17 years with a win over Manchester United in the Europa League final.
Frank joined Brentford in December 2016 and has been manager since 2018. He has established a reputation as a tactically flexible and shrewd coach who has improved players, especially those of a lower profile or who have not performed at other clubs.
At Tottenham, he will have a squad of higher quality — albeit one that finished below Brentford in the Premier League last season — and will be managing in the Champions League for the first time.
In that sense, it's a slight gamble from Spurs. Indeed, Frank has never won a trophy in his managerial career.
However, having had Antonio Conte and Jose Mourinho at the helm for spells since 2019, even those managers with elite-level pedigree have found it tough to lead Tottenham to success and Frank at least has plenty of Premier League experience.
Brentford have played in the top flight since 2021 and consistently punched above their weight.
After days of negotiations, a deal was struck between the two clubs on Thursday.
Spurs had quickly set their sights on Frank after deciding to dispense with Postecoglou.
Discussions between Tottenham and Brentford initially centred on Frank's current terms at the west London club, which were set to run until the summer of 2027 and contained a release clause reportedly in the region of £10million.
Also on Thursday, Tottenham announced Australian Mile Jedinak, Nick Montgomery and Sergio Raimundo - three members of Postecoglou's backroom staff - had officially left the club.
Ryan Mason departed earlier this month to accept his first managerial role at West Brom.
With AP