The 20-year-old winger, the son of former Manchester United midfielder Paul, enjoyed a superb debut season with the Seasiders last term and scored in the 2-1 play-off final defeat to West Ham in May.
Following Blackpool's Wembley heartache, Ince vowed to stay with the club to help them bounce back into the top flight at the second time of asking, and against the Lions he helped give Ian Holloway's men the perfect start.
The two sides were evenly matched early on as they eased their way into the new Championship campaign on a hot day in the capital.
Blackpool striker Gary Taylor-Fletcher was the first to carve open a chance on eight minutes only to curl over the crossbar, while Danny Shittu went close for Millwall with a downward header from a corner soon after.
The home side were denied an opener on 22 minutes when Andy Keogh found himself one-on-one with Matt Gilks but the Seasiders' goalkeeper produced a fine reflex save to keep out the striker's powerfully struck volley.
Chances were coming at both ends in the opening half hour, with Kevin Phillips drawing a save from Maik Taylor in the Millwall goal and Lions midfielder Josh Wright volleying wide.
Taylor was called on again to keep out chances from both Neal Eardley and Phillips, before Blackpool finally found a way past the veteran shot-stopper on 32 minutes with a well-taken goal.
The dangerous Ince drifted inside off the left and played a lovely one-two with Phillips before sending a deft, right-foot shot into the bottom right-hand corner.
The half-time whistle was a welcome sound for Millwall, who came out with renewed impetus after the break and almost levelled when Keogh flicked on James Henry's cross only for Jack Smith to miss the ball by a matter of inches at the far post.
But their hopes of gaining anything from the game took a huge dent when Ince bagged his second on the hour mark.
After good work from Phillips on the half-way line, Taylor-Fletcher lofted a ball over the top and the young midfielder outpaced the defence before finishing with aplomb high into the net with his left foot.
The visitors then started to frustrate their opponents as they bossed possession with some nice inter-play.
Wright went close to pulling a goal back only for his shot to sail into the side netting, while Darius Henderson's header from Liam Trotter's cross looped on to the roof of the net with three minutes to go as Millwall failed to find a way past Gilks.