Mujica has signed a three-year contract at Elland Road, running until the summer of 2022 and teams up with Carlos Corberan's under-23s.
So - here is everything you need to know about the Whites' latest recruit:
Height: 6 foot 1 inches
Career so far
Mujica joined Barcelona's academy in 2015 from Las Palmas - his place of birth - before stepping up to reserve team level, just one year later.
A few months after making his second-string debut, Mujica was asked to train with Barcelona first-team for their 2016/17 preparations and he proved a hit in front of goal.
Featuring alongside Lionel Messi, Mujica capped off a memorable afternoon by scoring in a 4-2 pre-season friendly win over Leicester City.
Mujica seemed to be making an impression and he continued his development with the B team only for a hamstring injury halfway through the season to halt his progress.
He was sidelined for nine months and shortly after his return, was loaned to UE Cornella for four months and scored five goals in 15 outings.
The attacker remained in the Barcelona B set-up despite being named in the first-team squad for a Copa Del Rey clash with Levante in January.
He ended his final campaign with seven goals in 33 outings and no first-team appearances. Mujica has represented Spain at under-18s and under-19s level.
Where will he fit it at Leeds
He will initially link up with Corberan’s under-23 side with a view to training with the first team.
Depending on his progress, he will likely remain in the Whites' second string, allowing him to get a full season of football under his belt in a new country.
That said, we saw last term Marcelo Bielsa is willing to give youngsters first-team opportunities, most noticeable Jamie Shackleton and Jack Clarke - with the latter earning a move to Tottenham.
Barcelona to Leeds - it is not the first time this has happened
The Whites have signed Kun Temenuzhkov and Oriol Rey from Barcelona since the arrival of Victor Orta as director of football.
Temenuzhkov made his first-team debut for Leeds in their FA Cup defeat to QPR in January while Rey spent last season back in Spain on loan at Conquense.
It could a cup competition which may present Mujica with his first-team chance, as we have witnessed with so many of the Whites' younger players.