Messi's second-half strike against Levante brought Barca the La Liga crown for the 26th time in the club's history, with 10 of them coming since the Argentine made his debut in the 2004-05 season, ESPN reprted.
Barca has now won back-to-back league titles under Valverde to add to its previous triumphs under Luis Enrique, Tito Vilanova, Pep Guardiola and Frank Rijkaard. The Catalan side has won eight of the last 11 and Messi is one of the constants.
He has scored 25 or more league goals in each of the last 10 seasons, with the goal against Levante taking him to 34 for the current campaign, and is the top scorer in the competition's history.
"Obviously Messi is at the core of all of this," Valverde said in his post-game news conference. "It's been an era marked by success in La Liga for the club. Coaches and players have come, gone and contributed but if there has to be one name above the rest, it's Leo's.
"We're not going to deny that. Everyone knows it. He marks everything we do. He marks our style of play. His competitive nature drives us all on."
Messi's teammate Luis Suarez added, "He is the best player in the world and the best of all time. You have to enjoy every minute you play with him. We're all proud of what him and what he does in every game."
Valverde opted to start Messi on the bench against Levante, resting him ahead of Wednesday's Champions League semifinal first leg against Liverpool.
However, after a goalless first half, Messi was brought on at the break and netted the only goal in the 1-0 win.
"That was always the plan," the coach insisted. "I was sure that he had to play some part because we have a big game on Wednesday and he has to remain active and score goals, which is what he does, and this one gave us the title."
It's the second season running that Barca has wrapped up the title with games to spare but they still hope to win more silverware this season. It remains in the hunt for the Champions League and the Copa del Rey.
"Winning the title by this distance and with games to spare against the rivals we have is difficult, especially two years running," Valverde said.
"We're so happy, seeing the fans enjoying themselves makes us all really proud. The difficult thing isn't winning, but to keep on winning. If you can manage that, it's because you're hungry to win.
"You have to keep on motivating yourself. Eight out of 11 [titles] shows how seriously the club takes this competition. Now we have other challenges ahead."
Barca was handed the trophy after the match and there was a fireworks display at Camp Nou.