Chloe Peplow opened the scoring on 44 minutes for the title-chasing Seagulls with the second and clinching goal arriving in the 92nd minute from Amanda Nilden.
Back in action after a midweek WSL 2 game against Millwall was postponed, Spurs were put under pressure in the early exchanges as Ini Umotong threatened and Danni Buet fired wide.
Katie O'Leary was denied one-on-one as Spurs got into the game and then both teams hit the woodwork - Jenna Legg for Brighton before Bianca Baptiste hit the upright with Lucy Gillett beaten.
Buet, Lucy Somes and Aileen Whelan tried their luck for Brighton while at the other end, Gillet saved from Wendy Martin.
Below: Renee Hector challenges at Brighton
Buet struck wide again on 43 minutes but the home team took the lead a minute later when Peplow's free-kick looped home.
Into the second half and Whelan touched wide Peplow's free-kick on 51 minutes and last-ditch defending kept out O'Leary. Ashleigh Neville then hooked away from Whelan in front of goal.
Spurs stepped up a gear in the final quarter. Gillett tipped over Coral-Jade Haines' volley on 69 minutes, Baptiste then had the ball in the net only to be denied by the offside flag and Andreya Ezekiel-Meade was denied a debut goal on 85 minutes when she clipped Hannah Mackenzie's pass over Gillett only for Vicky Ashton-Jones to get back and clear off the line.
So near yet so far - and Brighton doubled their lead in stoppage-time when Nilden slotted home from Umotong's pass.
Spurs are scheduled to return to action with a trip to Oxford in WSL 2 on Sunday 19 April.
Report from Khalid Karimullah at Brighton & Hove Albion Women FC, Culver Road
Photos with thanks to Wu's Photography
Brighton & Hove Albion: 1. Lucy Gillett, 6. Vicky Ashton-Jones, 5. Laura Rafferty, 3. Sophie Perry, 35. Chloe Peplow (8. Kirsty Barton 86), 14. Jenna Legg (10. Kate Natkiel 78), 4. Danni Buet, 11. Fliss Gibbons, 7. Lucy Somes, 16. Aileen Whelan (34. Amanda Nilden 60), 9. Ini Umotong. Substitutes (not used): 24. Sophia Pharoah, 36. Marie Hourihan, 17. Natalie Taylor.
Tottenham Hotspur Ladies: 21. Chloe Morgan, 29. Ashleigh Neville, 6. Renee Hector, 11. Jenna Schillaci, 19. Ryah Vyse, 4. Josie Green, 23. Coral-Jade Haines (45. Andreya Ezekiel-Meade 80), 10. Wendy Martin, 8. Bianca Baptiste, 14. Katie O’Leary (17. Lauren Pickett 76), 34. Rea Laudat (12. Hannah Mackenzie 66). Substitutes (not used): 1. Chloe Crook.