The 23-year-old, who signed a four-year deal with his new club and will wear the number nine shirt previously worn by Patrick Kluivert, said nothing would have persuaded him to return to his former side Real Madrid.
"If they had offered to pay 1000 million I would not have gone to Real Madrid because I would never have been happy," the Cameroon international told reporters at the Nou Camp.
"I gave all I could to make the Mallorca fans happy while I was there and now I will try and do the same at Barcelona."
Real Madrid, who had a 50 percent share in the player, were reported to be keen to use Eto'o as part of a deal to sign Liverpool striker Michael Owen but his insistence on joining the Catalan club gave them little option but to accept the move.
Real will receive 12 million euros for their share of the player and are expected to used the new funds to help finance the possible purchase of both Owen and Arsenal midfielder Patrick Vieira.
Eto'o is the seventh player to join Barca since the end of last season when they finished runners-up to Valencia in the Primera Liga and brings their total spending on new recruits to over 60
Portugal playmaker Deco, Sweden striker Henrik Larsson, French midfielder Ludovic Giuly and Brazilian defenders Juliano Belletti, Silvinho and Edmilson are the other new signings.
FIERY TEMPERAMENT
Eto'o's arrival will fuel speculation that Barca plan to offload Argentine striker Javier Saviola.
The Cameroon international, who scored 17 league goals last season, will take one of three berths for non-European Union players at Primera Liga clubs and that will increase the pressure on Barca to secure Spanish citizenship for other new signings.
Eto'o joined Real Madrid as a 16-year-old in 1997 but was loaned out to Leganes and then Mallorca -- who subsequently bought a half share in him -- to gain experience.
He went on to become the islanders' most influential player, renowned for his turn of speed, neatly taken goals and fiery temperament.
Eto'o formed a key part of Cameroon's gold medal-winning side at the Sydney Olympics and in their back-to-back African Nations Cup victories in 2000 and 2002.
He inspired Mallorca to victory in the Spanish King's Cup in 2003, scoring twice in their 3-0 win over Recreativo Huelva, and made a name for himself with spectacular goals against Real Madrid in the Cup and the league.