Millwall Lionesses slipped to a fifth successive defeat as Sunderland leap-frogged Aidan Boxall's charges to second place in the table, level on points with league leaders Leeds Carnegie.
Goals from Kelly McDougall and Steph Bannon sealed the win for the Black Cats with Ann-Marie Heatherson grabbing a late consolation.
Manager Boxall handed a first start for new signing Lizzie Edwards who joined from league rivals Watford during the week - with Angela Kiobel dropping down to the bench.
Sunderland began brightly as they pushed the home side back looking for an early goal. Natalie Gutteridge and Jordan Nobbs went close for the visitors whilst Meghan McKeag shot wide for Millwall.
The breakthrough came on 39 minutes following a strong run by Demi Stokes, who beat two defenders before cutting inside to set Kelly McDougall free on goal. Although Claire Lacey initially saved, McDougall followed up to slot home from an acute angle.
The Wearsiders continued to press as Gutteridge, McDougall and Nobbs had efforts beaten away by the busy Lacey.
Heatherson caused a scare for the visitors but her shot failed to trouble keeper Rachael Laws. Sunderland extended their lead on the hour, following a right wing corner from Kelly McDougall who provided an inchperfect delivery that skipper Steph Bannon rose highest to head home.
Millwall were stunned into action and had their brightest spell of the game and eventually pulled a late goal back through Heatherson who picked the ball up on the right, turned inside and drove a hard low shot into the bottom corner.
The Lionesses are back in action when they face Chelsea Ladies FC this Wednesday 28th October at Beckenham Town FC's Eden Park as they look to get back to winning ways in the FA Women's Premier League.
Millwall Lionesses: Claire Lacey, Dionne Lennon, Sarah Jones, Jordan Butler, Charlotte Gurr, Carly Eagles, Meghan McKeag, Emma Beckett, Ann-Marie Heatherson, Lindsey Morgan (Leah Jones), Lizzie Edwards. Subs not used: Lauren Phillips, Sinead Boyer, Angela Kiobel, Sinead McSharry