Harry and Meghan were among the high-profile guests present to watch Ellen DeGeneres and her wife Portia de Rossi renew their wedding vows.
The Duke and Duchess of Sussex looked on as the TV talk show host was surprised with the gesture as part of her 50th birthday celebrations.
Kardashian matriarch Kris Jenner officiated the ceremony, and US country singer Brandi Carlile also gave a special performance.
"Portia surprised me at her birthday party by renewing our vows," she wrote on Instagram.
"Thank you @KrisJenner for officiating and @BrandiCarlile for performing, and Portia for being the greatest gift to me, even on your birthday."
"These two are couple goals that continue to amaze me with how good they are together," Jenner said.
"A match made in heaven, two peas in a pod. Their love and commitment to one another is amazing and it makes me so happy that they have each other to love and cherish and grow."
DeGeneres told her wife: "I love you, I adore you and I would not be on this earth without you. You save me every day."