The trophy was Barca's to lose as they started the day with a one point lead over Real and the head-to-head advantage in their favour, and they held their nerve in front of a packed and expectant Nou Camp.
Valladolid's Luis Prieto scored an own goal after 27 minutes and soon after Pedro doubled the lead before Argentine World Player of the Year Lionel Messi wrapped up the victory with his 33rd and 34th league goals of the season in the second half.
Barca finished the season with coach Pep Guardiola's seventh trophy in two years and a Spanish league record of 99 points.
"I have huge admiration for what Real Madrid have achieved. They weren't champions only because the other team were just a little bit better," Guardiola told a news conference.
"We only lost one game all season, and this is down to the excellent, hard-working and humble group of players we have."
Malaga's draw saved them from them from drop but Valladolid were sent down to the second division along with Tenerife who lost 1-0 at Valencia, and Xerez who drew 1-1 at Osasuna.
Barca started incredibly nervously and a last-ditch block from Carles Puyol prevented Valladolid's Manucho from scoring a shock early goal.
They struggled to settle, missing the calming influence of suspended playmaker Xavi, until cheers spread round the Nou Camp after nine minutes as news filtered through that Malaga's Duda had netted against Real.
