The Hammers are due to host Southampton at the London Stadium at 3pm, with the Women's FA Cup final kicking off against Manchester City at Wembley at 5.30pm.
Having never previously reached the Women's FA Cup final, the club has been keen to find a way to get even more fans to Wembley to support the likes of Gilly Flaherty, Jane Ross and Alisha Lehmann for the biggest game in West Ham Women's history.
West Ham have explained that they requested the kick
However, the Premier Leagued rejected the proposed change, citing potential inconvenience to fans who had already bought tickets and arranged travel for the original 3pm kick-off.
A club statement read, "To give supporters the chance to attend both that game and West Ham United's women's FA Cup final fixture against Manchester City at Wembley later that day (5.30pm), the club had requested for the clash with the Saints to be brought forward to 12.30pm.
"Despite the club's very best efforts, it was decided by the Premier League that it wouldn't be possible due to the potential inconvenience caused to supporters who had already planned their journeys and purchased tickets.
"Therefore, the game will remain at the originally scheduled time of 3pm. West Ham United is naturally disappointed but would like to thank all of our loyal supporters and sincerely appreciates the fantastic backing they give to all who pull on the famous claret and blue."
Even though West Ham fans going to the Southampton game will be unlikely to make it to Wembley in time to see the Women's FA Cup final in person, they will still be able to catch it live on free-to-air television, with the contest being broadcast on BBC One.
As if to rub further salt in the wound after blocking West Ham's request to move kick-off by a couple of hours over inconvenience to supporters, Manchester City's Premier League fixture that weekend has been moved from Saturday 4 May to Monday 6 May at the behest of Sky Sports.
🚨 FIXTURE UPDATE 🚨— Supporter Services (@ManCityHelp) April 23, 2019
Please be aware that City v Leicester will now take place on Monday 6th May 8pm Kick-Off! #ManCityHelp
The game will instead now be broadcast live as 'Monday Night Football', an unpopular time slot with matchgoing fans.