Full-time score from St James' Park
Two second half strikes from Lions new boy Chris Taylor saw Kenny Jackett's men come back from a 2-1 half-time defecit to beat Exeter City 3-2 at St James' Park.
Liam Feeney had given Millwall the lead before the Grecians turned the game on its head with goals from Arron Davies and Alan Gow before the break.
But Taylor, one of six Millwall subs, netted his first goals since his move from Oldham to secure the victory.
Feeney put Millwall in front after just five minutes with a curling effort into the bottom corner from the left edge of the box.
Just past the quarter hour, David Forde save a Liam Sercombe half-volley as the home side found their stride.
Gow had a hand in the second, winning a free-kick which he took himself and when Forde punched clear, O'Flynn headed the ball back for Davies to score.
Gow then scored a fine individual second, dancing through the Millwall defence before netting from close range.
After the beak, Cureton missed a good chance for Exeter before The Lions drew level when Taylor was on hand to slot home after Scott Malone's driven cross was parried by Rhys Evans.
Darius Henderson then headed wide when well placed but the winner wasn't long in coming as Taylor finshed from another Malone cross.
Further chances came and went at either end, but The Lions held on for the win.
Exeter City:Evans, Amankwaah, Baldwin, Coles, Moore-Taylor (Wannell), Sercombe (Keohane), Oakley (Frear), Bennett (Doherty), Davies, O'Flynn (Cureton), Gow (Bauza).
Millwall: Forde, Smith (Dunne), Ward, Osborne, Malone (Barron), Henry (C Taylor), Abdou (Racon), Trotter (Wright), Feeney, N'Guessan, Marquis (Henderson).