The Shiv Sena had earlier decided to boycott the swearing-in ceremony because of “constant humiliation” despite claims of talks being held for a possible tie-up.
Shiv Sena had said, “We have constantly been humiliated by the BJP, which has not gone down well with our MLAs.
Devender Fadnavis, 44, is serving a fourth-term as MLA from Nagpur.
He was elected unanimously by the party for the CM's post.
The oath taking ceremony will be administered by Governor C Vidyasagar Rao at Wankhede Stadium in the presence of Prime Minister Narendra Modi, several of his Cabinet colleagues, Chief Ministers of BJP-ruled states, corporate leaders, Bollywood stars and other celebrities.