A Fernando Amorebieta (23) own goal set Liverpool on their way at Anfield after Luis Suarez's flicked header hit him and flew him. Martin Skrtel's bullet header from Steven Gerrard's corner on 26 minutes made it 2-0 and Suarez capped off a fine passing move to make it 3-0 with only 36 minutes on the clock.
Suarez (54) grabbed his second firing home at the near post after great work by Henderson to make it 4-0 as Liverpool cruised into second spot.
Mourinho's teams were never beaten on their home patch in the top flight during Mourinho's first spell in charge, and they have embarked on another undefeated run since the Portuguese boss returned to the club in the summer.
They were in peril at 2-1 behind against the Baggies deep into stoppage time, however referee Andre Marriner deemed Steven Reid to have fouled Ramires in the penalty area and handed Chelsea a spot-kick.
Eden Hazard, in Mourinho's bad books earlier in the week after a passport blunder, converted with a cheeky pass into the bottom right corner.
It meant Mourinho's former assistant Steve Clarke was denied a famous win over his old boss, whose team nevertheless slipped to fourth place in the table, behind Southampton and Liverpool, plus leaders Arsenal.
Chelsea went ahead with a close-range poacher's finish from Samuel Eto'o right on 45 minutes, but Shane Long gave a warning of what was to come when he headed against the left post early in the second half.
Long equalised in the 60th minute, nodding in from close range after Petr Cech powered a thumping header from Gareth McAuley, and Stephane Sessegnon then fired the Baggies ahead eight minutes later when his low left-footed shot embarrassed the Chelsea goalkeeper.
West Brom protested long and hard about the late penalty, which looked soft, but Hazard took full advantage.
Morgan Schneiderlin (16) put Saints ahead before a Ricky Lambert penalty made it 2-0 on the half-hour mark. Then a brilliant Adam Lallana strike made it 3-0 before Yannick Sagbo reduced the arrears midway through the second half.
Steven Davis had the last word though as he made it 4-1 to the hosts on 88 minutes.
Leandro Bacuna (76) scored a fine free-kick as Aston Villa ended their goal drought against Cardiff with Libor Kozak (84) making the game safe for the hosts at Villa Park as they climbed into the top half of the table.
In the late game Norwich came from a goal down at half-time to beat West Ham 3-1.
Ravel Morrison put the Hammers ahead, but Gary Hooper's penalty, a Robert Snodgrass free-kick and a stoppage time strike from Leroy Fer handed the Canaries a deserved 3-1 win.