The television presenter and columnist has accepted the role with Speur-Ghlan (Gaelic for blue skies), which delivers early intervention for young children diagnosed with autism or developmental delays.
It uses a range of research-based approaches, including play and music-based therapy sessions, to help young children aged between six months and five years.
Miss Palmer Tomkinson, who plays the piano and sings, has an interest in autism from previous experience supporting music charity Nordoff Robins.
Miss Palmer Tomkinson, said: "It is a huge honour to have been chosen as patron of the Speur-Ghlan charity; I have been following with admiration the tireless work it does to bring help to children who have an autism diagnosis or developmental delay, and very importantly, the families and friends who surround them."
Speur-Ghlan founder Ruth Glynne-Owen said: "It's fantastic we have someone of Tara's calibre backing us as it'll make a huge impact."