Lionel Messi and Luis Suarez each scored in a routine if underwhelming win at home to struggling Levante, with Paulinho increasing their lead in added time.
Record signing Philippe Coutinho did not attend the game after completing his 142-million-pound ($192.67-million) move from Liverpool to Barca on Saturday.
Ousmane Dembele however made his first league start in more than three months.
Messi was back in the starting line-up after missing the King’s Cup draw with Celta Vigo on Thursday.
He marked his 400th game in La Liga by opening the scoring in the 12th minute, when he volleyed Jordi Alba’s cushioned header into the net.
Suarez struck his fifth goal in four games running by controlling a cross from Sergi Roberto and slamming the ball high into the net in the 38th minute.
Barca relaxed a little after the break, but Brazilian international Paulinho added an extra shine to the win by tapping in as the game drew to a close.
He was scoring for the seventh time in the Liga, making him the top-scoring midfielder in the Spanish top flight.
Barca are nine points ahead of nearest challengers Atletico Madrid and 17 clear of champions Real Madrid, who were visiting Celta Vigo later on Sunday.