In a video shared on the Spice Girls' Instagram account, the women posed in shirts from Beckham's 2021 Pride collection that read, "Proud and wannabe your lover."
"100 per cent of the proceeds go to the brilliant @aktcharity to continue funding the wonderful work they do to combat youth homelessness in the LGBTQ+ community. #Pride2021 #FriendshipNeverEnds," adding a Pride rainbow flag emoji, the caption read.
The $120 (£85) white tees are emblazoned in rainbow text, with the word "wannabe," printed in bold black lettering.
Beckham also shared the video on her Instagram account explaining in the caption why Pride Month is important to her.
"Pride to me is a celebration of being completely yourself and this year's T-shirt is a reminder of that. The Spice Girls really championed accepting yourself and others, being kind, having fun and just living your best life!" the mom of four wrote.
She added, "The LGBTQ+ community is so close to my heart and I'm so proud to be supporting Pride 2021 with the girls and akt again this year."
This is Beckham's third collaboration with the Albert Kennedy Trust, and the first time she has involved the Spice Girls.