Full-time from The Den
Gregory was on hand to head The Lions in front after just eight minutes and Neil Harris' charges did not look back, with Jed Wallace's sublime 24th-minute free-kick making it 2-0 before skipper Steve Morison crowned a comfortable victory with a third from the penalty spot three minutes from time.
Both The Lions and Tangerines went into action needing points to boost their hopes of promotion and avoiding relegation respectively.
It was quite clear from the opening seconds that this was going to be Millwall's day as Harris' charges quickly put the visitors to the sword.
Mark Beevers went close on five minutes with an effort from Shane Ferguson's corner that was hooked over by a desperate clearance from Hayden White as The Lions asked early questions of a Blackpool defence that had conceded 43 goals prior to Saturday's match.
That tally soon became 44, when Gregory stole in to meet a long throw from Edwards, squeezed past two defenders and sent a firm header into the roof of the net.
The Lions at times produced some delightful, slick, attacking football and a sweeping 17th-minute move involving Mahlon Romeo and Wallace on the right set up Gregory, whose glancing header dropped narrowly wide of the left upright.
Another lovely inventive passage of play on the opposite flank with Ferguson and Edwards came to an abrupt halt when the latter was sent crashing to the ground in a central position 20 yards out. Up stepped Wallace to curl the resulting free-kick home, with the Blackpool wall in disarray.
Millwall's front line, with Morison using all his guile and experience, proved a constant threat and with right-back Romeo getting into great positions on the overlap, further goals always looked likely from a dominant first-half display.
Jimmy Abdou started a wonderful move on the half-hour mark, winning possession on the edge of his own area and picking out Morison on the right. The skipper dummied Clark Robertson and set off down the wing, but his final cross to try and pick out the unmarked Gregory fell just short and the ball was cleared for a corner.
Morison and Romeo combined moments before the break with another slick interchange, but the danger was cleared as Blackpool somehow went in just two goals behind at the end of what was a sorry first-half showing by the Seasiders.
Although Blackpool were improved after the break, it was Millwall who were soon on the attack again. Busy midfielder Ben Thompson went close with a low drive on 57 minutes moments after White had been booked for a bodychecking Edwards. Unfortunately Edwards was forced off the field on 63 minutes, still feeling the affects of that challenge.
Millwall: Archer, Romeo, Edwards (Upson, 65mins), Beevers, Webster, Abdou, Thompson, Ferguson, Gregory (O'Brien, 78mins), Morison (Philpot, 87mins), Wallace. Subs not used: Forde, Williams, Onyedinma, Nelson.
Bookings: Thompson (37mins), Beevers (78mins), Upson (79mins)
Scorers: Gregory (8mins), Wallace (24mins), Morison (87mins, pen)
Blackpool: Doyle, White, McAlister, Robertson (Boyce, 44mins) , Potts, Redshaw, Herron (Cullen, 63mins), Aldred, Philliskirk, Aimson, Ikpeazu (Paterson, 83mins). Subs not used: Lyness, Jones, Smith, Yeates.
Bookings: Ikpeazu (35mins), Herron (45+2mins)
Att: 9,753 (away 245)
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