The Catalan giants triggered the Danish striker's release clause and he'll join up with the team immediately.
BREAKING: Barcelona have completed the emergency signing of Leganes forward Martin Braithwaite after activating his €18 million release clause.— ESPN FC (@ESPNFC) February 20, 2020
He joins on a contract until June 2024. pic.twitter.com/fKTu3socGx
According to OPTA, Braithwaite has been involved in a goal every 242 minutes with Leganés in Liga 2019/20 (six goals & two assists in 1934 minutes), 28th ratio among the 41 forwards who played at least 1000 minutes in the Spanish top-flight this season.
That stat is quite a mouthful, but it indicates his usefulness in front of goal.
The signing has been deemed somewhat controversial because of Barca obtaining special permission from LaLiga to make an emergency signing outside the transfer window after Ousmane Dembele was ruled out for six months with a serious hamstring injury.
LaLiga rules allow clubs to apply to make new signings if a player is ruled out for more a period exceeding five months.