Araujo's injury came after he and Gavi banged heads challenging for the same ball. Araujo stumbled on for a few seconds before dropping to the floor as a concerned Iago Aspas and Eric Garcia called urgently for the medics.
The Uruguayan was put into the recovery position and after a few minutes, he was lifted into an ambulance that had driven onto the pitch.
Aubameyang's double either side of half-time came after Memphis Depay had opened the scoring at Camp Nou. Celta pulled one back through Aspas but any hopes of a comeback were dashed when Jeison Murillo was sent off just before the hour.
"We were effective but we didn't play well," said Xavi. "It was simpler against 10 men but we struggled against 11."
Barca move seven points ahead of Sevilla and eight in front of Atletico Madrid, with Sevilla and Atletico playing each other at the Wanda Metropolitano on Sunday.
Real Madrid, who have already been crowned champions, sit nine points clear of Xavi Hernandez's side at the top of the table, with a game in hand.
Securing qualification for next season's Champions League last weekend means Xavi's primary objective has already been achieved but the club's dire financial situation means the team can still not afford to let up.
Every place towards the top of La Liga is worth around seven million euros while qualifying for the four-team Spanish Super Cup by finishing in the top two is worth another eight million euros to the Catalans.
They should have the runners-up spot sewn up after another victory that owed much to Aubameyang, the 32-year-old scoring his 12th and 13th goals since joining Barcelona from Arsenal in January.
Aubameyang's electric early form has slowed a little in recent weeks but it is hard to think of a Barca player who has made a bigger contribution to their resurgence in the second half of the season.
Depay's game-time has suffered as a result of Aubameyang's form but they both started against Celta and it was Depay who gave the hosts the lead in the 30th minute, sweeping in after s superb run down the right by Ousmane Dembele.
Depay then turned provider for Aubameyang's first as he latched onto Jordi Alba's through ball and crossed for his Gabonese teammate to finish on the turn four minutes before half-time.
Three minutes after the restart, it was three as Dembele repeated his earlier trick, driving down the right, rolling left, this time for the sprinting Aubameyang to steer into the corner.
Aspas capitalised on a Barcelona error as Araujo was caught on his heels after Marc-Andre ter Stegen passed out to him in the penalty area. But eight minutes later, Murillo was sent off for preventing Depay from going through and Celta's momentum was gone.
Real Betis had earlier kept their top-four hopes alive by easing to a 3-0 win away at Valencia. Willian Jose, Sergio Canales and Borja Iglesias all scored goals in the second half.
Betis closed the gap to Atletico Madrid in fourth to three points, with Atletico playing a game in hand away at Elche on Wednesday.