The 26 year old singer wrote the letter on behalf of her partner Simon Konecki and their two year old son Angelo, to say sorry for not making it to the music legend's wedding.
She wrote: ''Biggest congratulations my loves. Have a wonderful day. I'm sorry we are not there. See you in 2015. Love Adele, Simon and Angelo. x. (sic)''
Elton posted a picture of the letter which Adele wrote from floral designer Rob Van Helden, who also attended the nuptials.
He added the caption: ''The perfect end to the perfect day. So many kind thoughts and wishes. #ShareTheLove (sic)''
Other photos posted included one of the pair's wedding menu which featured wild mushroom soup with truffle cream to start, followed by a beef rib and caramelised onion pie and then a warm chocolate pudding with vanilla ice cream for dessert.
Elton also added the caption: ''Our little ring bearers are fast asleep, and their shoes are polished and ready for tomorrow's [email protected] #ShareTheLove (sic)''
While Adele didn't make the spectacle, other stars had some festive fun at the bash including David and Victoria Beckham and their four children, Brooklyn, 15, Romeo, 12, Cruz, nine, and Harper, three, as well as Ed Sheeran, David Williams and his wife Lara Stone, and Elizabeth Hurley and her 12-year-old son Damian.
Credit Image:Gallo Images.Elton John