Barcelona players were able to begin their celebrations at halftime of their 1-0 win over Celta on Wednesday because Valencia, the only team within reach of first place, had already fallen, 2-1, to Mallorca.
The Catalan club coached by Dutchman Frank Rijkaard became the first team to repeat as La Liga champions since it pulled off the feat in 1998-99. Starring World Player of the Year Ronaldinho, Barcelona faces Arsenal in the Champions League final May 17.
Barcelona has now won 18 La Liga titles, second to archrival Real Madrid's 29 titles.