Sunday's match at the Nou Camp was also an emotional one as it witnessed the return of Eric Abidal after a year out following liver surgery.
Fabregas commanded the spotlight in the injury-enforced absence of Lionel Messi, scoring three and setting up two for Alexis Sanchez as Barca romped home.
They were also inspired by Tito Vilanova, who was on the Nou Camp touchline for the first time since January after undergoing treatment for cancer.
However, it was Abidal's appearance that brought the Catalans to their feet with the Frenchman given a standing ovation when he replaced Gerard Pique in the 70th minute.
Cristian Tello had Barcelona's first shot of the match but sent his effort wide at the far post when unmarked on the left of the area.
Mallorca were holding their own but there was a feeling of inevitability and there was no surprise when Barca finally made the breakthrough with two goals in two minutes.
Fabregas carried the ball from midfield and played a one-two with Alexis before steadying himself and coolly slotting the ball home across goalkeeper Dudu Aouate.
Mallorca's heads went down and they soon found themselves 2-0 adrift - this time Fabregas cut inside on the left of the area before unleashing a shot which Aouate pushed away from goal only for Alexis to follow up and fire home.
The visitors appealed for a penalty when Jose Carlos Nunes' hooked shot appeared to hit a combination of Thiago Alcantara's chest and arm in front of goal.
Aouate parried Andres Iniesta's shot after he had gone past a static Mallorca defence, but the visitors had by no means given up.
Tomer Hemed's drilled shot went just wide of the right post but Alejandro Alfaro squandered a golden opportunity when he put a header wide when unmarked at the far post.
They were made to rue their profligacy when Barca got two goals in a minute.
An intricate passing move ended with Fabregas laying a first-time ball off to Alexis on the right of the area which he reciprocated for Fabregas to drill home.
The former Arsenal captain was involved everywhere and he provided a superb pass over the top for Alexis, who had got between two defenders, controlling the ball with his right before slotting home with his left.
Fabregas wrapped up his hat-trick seconds after the restart when he collected Iniesta's threaded ball and checked inside the defender before slotting home from close range.
Mallorca had the ball in the net but Alfaro was judged offside, although replays suggested that may have been an incorrect decision.
It was one-way traffic from then on, Barca creating chances at will.
And it was the appearance of Abidal on the touchline and subsequent foray onto the field with a little more than 20 minutes remaining that prompted the biggest roar around the Nou Camp.
The 33-year-old France defender had not played for Barca's senior side since February 2012. He underwent a liver transplant last April, having previously had surgery to remove a tumour in March 2011.