Captain Sergio Busquets and defender Jordi Alba also played at home for the last time, in the club's penultimate league match of the season, and were awarded warm farewells by the sell-out crowd.
Ansu Fati struck twice in the first half and Gavi added one after the break as the Catalans triumphed in style.
Marc-Andre ter Stegen earned his 26th clean sheet of the season, equalling the all-time record in the division, set by Deportivo La Coruna's Francisco Liano in the 1993-94 campaign.
The only bad news for Barcelona came when defender Alejandro Balde was taken off injured in the first half.
The left-back was lunged at by Mallorca's Amath Ndiaye, who was sent off.
Balde will be out for six to seven weeks, missing the club's final La Liga game and the Nations League final four with Spain.
"It's a sad day, when you play so many games here, Camp Nou is your home," Ter Stegen told DAZN.
"It hurts to say goodbye to team-mates who have been so important in my career like Busquets and Alba have, I wish them and their families the best."
Camp Nou, inaugurated in September 1957, has been one of football's most iconic stadiums since then.
Barcelona will play their home games next season at the Olympic Stadium on Montjuic, a hill in the city, aiming for a return to the rebuilt Camp Nou in November 2024 if construction goes to plan.
The Catalans took the lead when Gavi fed Fati for an easy finish, and the forward struck again after Robert Lewandowski set him up.
Jules Kounde and Lewandowski hit the woodwork in the second half and Ousmane Dembele had a header cleared off the line, before Gavi thrashed home the third.
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