Shiv Sena took this decision after BJP chief Uddhav Thackeray and Fadnavis invited him for the ceremony.
The oath-taking ceremony is taking place at Wankhede Stadium in Mumbai.
Fadnavis, 44, is all set to take oath as the 27th chief minister of Maharashtra and the first Bharatiya Janata Party's (BJP) CM in the state at a grand ceremony at Wankhede Stadium.
The Shiv Sena had earlier decided to boycott the oath-taking event. The party was unhappy over not getting a desired deal to participate in the BJP-led government.
"We have constantly been humiliated by the BJP, which has not gone down well with our MLAs. As our MLAs feel that BJP did not give us due respect, why should we attend the oath-taking ceremony?" Shiv Sena MP Vinayak Raut had said on Thursday.