Perhaps in a sign of the growing pressure on his position after a run of one win in seven games in all competitions, Frank Lampard named a strong team for the visit of the League Two side to Stamford Bridge.
Mason Mount's fine strike on the midfielder's 22nd birthday opened the scoring before Timo Werner ended a goal drought of 827 minutes shortly before half-time.
Callum Hudson-Odoi got his side's third and only goalkeeper Mark Halstead denied the Blues further goals until Kai Havertz powered in a late header.
Morecambe almost snatched a shock lead with 11 minutes played, Kepa Arrizabalaga - on his 100th Chelsea appearance - doing well to stop Adam Phillips's drilled cross from going over the line.
Chelsea's breakthrough came with 18 minutes gone, Mount given time to pick his spot from 20 yards out, leaving goalkeeper Halstead with little chance.
Werner had missed an early header but could not pass up the chance to make it 2-0 just before half-time, the forward prodding into an empty net after Havertz headed back across goal.
Any lingering doubts about the result were removed four minutes after the restart, Hakim Ziyech's pass beating the offside trap and allowing Hudson-Odoi to power a shot through Halstead.
Havertz should have made it 4-0 only for Halstead to block at the near post and the keeper made a second fine stop to deny Christian Pulisic on the rebound, the keeper's best moment of a good display.
He could do nothing to prevent Haverz from finding the back of the net five minutes from time, though, the midfielder meeting Cesar Azpilicueta's deep cross with a thumping header.