After the movement was banned following the assassination of Stewart, he continued the struggle with the Sarawakian Youth Front, led by Ahmad Zaidi Adruce.

Fadillah first ran for parliament in the 11th Malaysian general election, having previously been an official in Parti Pesaka Bumiputera Bersatu (PBB) and a lawyer.

[9] Following the defeat of Barisan Nasional (BN) in the 14th Malaysian general election, Fadillah was made chief whip of the opposition Sarawak Parties Alliance (GPS) in the House of Representatives of Malaysia.

Consequently, Yang di-Pertuan Agong Al-Sultan Abdullah Ri'ayatuddin Al-Mustafa Billah Shah proposed the formation of a unity government, with Anwar Ibrahim eventually appointed as its leader on 24 November 2022.

In a cabinet announcement on 2 December 2022, Fadillah was appointed Deputy Prime Minister alongside Ahmad Zahid Hamidi.

Fadillah's appointment is of historic significance as he is the first individual from Sarawak to hold the country's second-highest political office since the formation of Malaysia.