Benik Afobe frustrated AFC Bournemouth as the former Cherries man cancelled out Dominic Solanke's first half opener.
Solanke was alert just before half-time to slam home Stacey's hopeful ball into the box, the first real moment of quality from the Cherries.
However, Afobe, who appeared 70 times for the club between 2015 and 2018, tucked home in the 67th minute to ensure the Cherries went home with just a point.
Manager Scott Parker made two changes to the side that played Derby on Sunday, with Gavin Kilkenny replacing Lewis Cook and Jamal Lowe replacing the suspended Philip Billing.
Millwall started brightly and created the game’s first chance after 10 minutes as Murray Wallace rose well to meet a Scott Malone corner, but the left back’s header looped just over the bar.
The Cherries settled shortly after and began to dominate possession but struggled to create a clear-cut chance.
Jaidon Anthony had the visitors’ first sight of goal after 25 minutes as he latched onto a pass from Leif Davis on the half way line and charged into the box, where he cut inside and saw his right footed shot deflected over the bar.
A moment of controversy followed as the already-booked Gavin Kilkenny went down in the Millwall box, leading to appeals from the home side for a second yellow card. After a brief coming together involving a number of players, the referee allowed play to continue.
The home side rallied after the incident but it was the Cherries who ended the half on top and they might have gone in front as Ryan Christie intercepted on the half way line and advanced into the area, only to be crowded out as he looked to cut inside and shoot.
The deadlock was broken on the stroke of the break, as Jefferson Lerma did well to keep the ball alive after a corner was cleared before cutting back to Stacey, whose cross found its way to Dominic Solanke at the back post.
The striker made it 16 goals for the season at the second time of asking, poking the ball home from close range after his initial header was blocked.
Solanke could have made it two early in the second half as he latched onto Ryan Christie’s pass from the edge of the box, but couldn’t get the ball out of his feet and saw his left-footed shot well blocked.
Christie was in the action again shortly after, picking up the ball on the right flank and cutting inside to shoot, but Bialkowski collected comfortably.
Millwall began to find their feet and might have equalised just before the hour but for a last ditch tackle from Gary Cahill. The Cherries captain slid in to brilliantly deny Afobe as the striker collected a long ball from Shaun Hutchinson and shaped to shoot from eight yards.
Afobe went one better after 67 minutes as he chased down substitute Tom Bradshaw’s header to break into the box and fire past Mark Travers with a right-footed effort.
The home side dominated the remainder of the game and nearly went ahead after Billy Mitchell evaded three tackles on the left flank before cutting inside and curling a shot just over.
Jefferson Lerma became an auxiliary centre-back for the final minutes as the Cherries moved to a back-three and made a crucial intervention as Afobe fired across goal, preventing Wallace a tap-in.
The Colombian celebrated like he'd scored, and understandably so knowing that his intervention ultimately ensured the Cherries went home with a point.
Millwall: Bialkowski, McNamara, Hutchinson, Ballard, M Wallace, Malone (Ojo, 66), Saville, Mitchell, J Wallace, Bennett (Bradshaw, 65'), Afobe.
Unused subs: Kieftenbeld, Smith, Pearce, Evans, Long (g/k).
AFC Bournemouth: Travers, Stacey, Mepham, Cahill, Davis, Lerma, Kilkenny (L Cook, 63), Christie, Lowe (Marcondes, 79), Solanke, Anthony (Rogers, 90+1).
Unused subs: S Cook, Ibsen Rossi, Moriah-Welsh, Nyland (g/k).
Booked: Kilkenny, L Cook.
Referee: Dean Whitestone.