Among the substitutes for the second time in a week, Phillips had only been on the pitch for two minutes of Saturday's Championship clash when he emphatically found the top corner from the edge of the area with an hour gone.
Millwall had found the net 10 times in a run of three straight wins but only threatened sporadically against a miserly Seasiders backline in which Alex Baptiste excelled.
A late onslaught from the visitors failed to materialise and Ian Holloway's side held out for back-to-back victories for the first time since the opening games of the season to move into the play-off places.
Blackpool made one enforced change form Wednesday's 5-0 thrashing of Leeds as Neal Eardley came into the defence in place of Ian Evatt, who collected his fifth booking of the season at Elland Road.
Kenny Jackett named the same Millwall side that recorded consecutive victories over Leicester, Ipswich and Coventry.
Following some quiet opening exchanges Blackpool midfielder Keith Southern brought the game to life in the eighth minute.
First Lions goalkeeper David Forde tipped his well struck 25-yard drive around the post, and from the resulting corner Southern found space for a free header that was cleared off the line by Jack Smith
With 20 minutes on the clock Smith proved considerably less reliable when his untimely slip allowed Neal Eardley to advance down the right flank and cut back to Southern who skied his effort from the edge of the area.
Lomana LuaLua, fresh from a midweek brace on his full Blackpool debut, charged at the visiting defence in the 25th minute and skilfully shifted the ball onto his left foot to bring a splendid save out of Forde as his shot arched towards the corner.
Millwall finally made an impression in their opponents penalty area when top scorer Darius Henderson peeled off to the far post and steered Liam Feeney's corner goalwards, only for Baptiste to intervene.
Baptiste caused some set piece problems of his own at the other end but headed over when he connected with Ludovic Sylvestre's delivery.
The deadlock remained in place as the hour approached and Holloway withdrew Southern to introduce Phillips.
Within minutes the veteran striker made the breakthrough with a sublime curling effort on the turn from the edge of the area.
Blackpool failed to effectively press home the advantage and Baptiste was forced to scramble clear after Liam Trotter wrought havoc in the home side's box.
Phillips almost doubled his tally with five minutes remaining when he scuffed Eardley's cross against the post.