The competition is part of the KFC Christmas campaign that launched two weeks ago. It asked viewers to tweet about a conflict in their lives they wanted to resolve.
Bartle Bogle Hegarty created the campaign. Fabric Worldwide handled the social media activity.
Patel was selected as the winner and will star in a 60-second musical-style spot featuring a specially written song.
She tweeted to @KFC_Choir, "I want to make peace with [friend Sheena Jagjiwan] as we are going travelling together for a month. It starts with 24hr flight".
Patel and the KFC choir will sing together in tomorrow’s ad to salvage the friendship before the trip to Australia.
Lyrics include: "Let’s both go down under with no anger inside us, cos we don’t know where we’re going and we’re terrified of spiders."
Meg Farren, the marketing director of KFC, said: "We’re thrilled with the engagement and response we’ve had towards the campaign and are really excited to have chosen a worthy winner."
The original two-and-a-half minute ad, which aired during an 'X Factor' break on 30 November, featured characters and a choir singing about putting their differences aside over a shared love of KFC chicken.
It has now been viewed over 400,000 times on YouTube and is available to download on iTunes and stream on Spotify.
The campaign will run until 29 December.