With one game left Barca hold a four-point lead ahead of rivals Real.
Luis Enrique's men, chasing a treble, face Athletic Bilbao in the Spanish cup on 30 May, before playing Juventus in the Champions League final on 6 June
And they could yet repeat the feat of 2008-09, when they won a historical treble under Pep Guardiola.
They have scored 108 goals so far in the league, with a fixture at home to Deportivo La Coruna still to come.
Their front three of Messi, Neymar and Luis Suarez have been prolific, netting 115 goals between them in all competitions.
Barca had a trophyless campaign last time round under Tata Martino, but former Barca and Real midfielder Enrique has turned the club's fortunes around by winning the title in his first season in charge.
Carlo Ancelotti's Real side were hoping Barca would slip up in order to take the title race to the final day, but although Ronaldo took his tally to 45 goals in the league in a 4-1 victory over Espanyol, Messi's moment of magic was enough for Barca to win their fifth championship in seven years.
Messi's 41st league goal of the season ensured that Real Madrid will finish the final.
