The in-form front man scored twice in a dominant first half which saw the Shrimps lead 3-0 at the break after Rhys Turner opened the scoring after just two minutes.
The home side improved in the second half and got a lifeline in the 77th minute when James Collins scored his 18th of the season from the penalty spot but the Shrimps held on comfortably for a fine three points.
It was the perfect reply to the midweek reverse against Barnet and leaves the Shrimps with just one defeat in 2017.
Jim Bentley made five changes to the side that lost 1-0 against Barnet but his side settled into the game quickly and went ahead after just two minutes when Michael Rose crossed from the left and Turner was unmarked to plant a powerful close-range header past Glenn Morris.
The Shrimps doubled their advantage four minutes later. Antony Evans, who had a fine debut, fed Mullin down the right and he raced unchallenged into the box before cutting inside and sliding the ball through Morris’ legs.
Crawley hit back briefly with Shrimps keeper Barry Roche saving Mark Connolly’s long-range effort at the second attempt before making a smart save from Collins’ powerful drive 15 yards out in the 26th minute.
Normal service was soon resumed when the Shrimps went 3-0 up in the 40th minute.
Morris pulled off a brilliant save to push away Mullin’s clever lob after Rose had smashed the ball downfield and split the home defence. The reprieve didn’t last long however as Crawley failed to clear the corner and Mullin’s shot took a deflection that took it beyond Morris’ despairing dive.
The home side brought on Rhys Murphy for Kaby Djalo at the break but they nearly conceded a fourth in the 53rd minute when Morris had to come haring out of his goal to dispossess two Morecambe players.
Lee Molyneux side-footed inches wide from Evans’ inviting low cross and it wasn’t until the last 20 minutes before the home side finally began to threaten.
Murphy won the penalty in the 77th minute after drawing an off the ball foul from Andy Fleming and Collins buried the penalty into the bottom right-hand corner.
A minute later Josh Lelan squandered a great chance when a corner dropped to him but his volley went well wide and just about summed up a flat, lacklustre performance.
Man of the match Morris made a great reflex save to deny substitute Aaron Wildig and Molyneux saw an effort cleared off the line by Connolly but despite seven minutes of stoppage time the Shrimps held on comfortably to pass thre 40 point mark for the season in style.
Crawley: Morris; Young, Connolly, Lelan (Bawling 90), Roberts; Henderson, Djalo (Murphy 45); Boldewijn, Smith, Cox (Clifford 70); Collins. Subs not used: Mersin, Payne, Blackman, Yorwerth.
Morecambe: Roche, Wakefield, Edwards, Whitmore, Winnard, Rose, Fleming, Evans (Wildig 68), Molyneux, Turner (Ellison 60), Mullin (McGowan 90).Subs not used: Nizic, Jordan, Hedley, Conlan.
Attendance: 2,091 (49 Morecambe)
Referee: Charles Breakspear.