Barca put six goals past the beleaguered visitors before half-time en route to their largest ever opening-day success.
While they could only manage one more in the second period - when summer signing Neymar was brought on for his league debut - they had already served notice that there would be no early jitters under their new boss.
Manchester United target Cesc Fabregas put in a man-of-the-match display and was involved in five of the seven goals as he left it to Lionel Messi (two), Pedro (two), Alexis Sanchez, Dani Alves and Xavi to get on the scoresheet.
Isco enjoyed a dream debut for Real Madrid by notching a late winner against Real Betis at the Bernabeu.
The former Malaga man rose above the defence to head in a cross from Marcelo with just four minutes remaining to deliver the three points to Carlo Ancelotti in his first game in charge of Los Blancos.
Before the 21-year-old struck, the game had looked to be heading for a stalemate after Betis took an early lead through Jorge Molina, which was then cancelled out by Karim Benzema.
The visitors gave a bold first-half performance but slowed down in the second half, allowing Madrid a host of chances, none of which they could convert until Isco finally pounced.
Diego Costa scored twice as Real's city rivals Atletico opened with an impressive win away to Sevilla.
The 24-year-old Brazilian, a reported target for Liverpool this summer, struck in each half before substitute Cristian Rodriguez's superb third in stoppage time.
Sevilla more than played their part in an open and entertaining game but had only Diego Perotti's long-range goal in the first half to show for their efforts.
Granada got their campaign off to the best possible start with a nervy three-point haul at Osasuna.
In a match between two teams who narrowly avoided the drop last season, the visitors seized the half-time initiative with goals from Youssef El Arabi and Hassan Yebdi.
Francisco Punal then replied for Osasuna before Piti missed a penalty for Granada, but Lucas Alcaraz's men held on for an opening win.
Sunday's La Liga Results