"We will implement the 13A within a unitary framework," Wickremesinghe said in his maiden address to parliament convened for the first time since President Maithripala Sirisena succeeded Mahinda Rajapaksa after the January 8 presidential election.
Rajapaksa's majority Sinhala nationalist regime was opposed to conferring full powers to the provincial councils, including the Tamil-dominated regions.
The issue of devolution of power also featured during Sri Lankan Foreign Minister Mangala Samaraweera visit to India this week.
The 13th amendment that followed the Indo-Sri Lankan Accord of July 1987 signed between then Prime Minister Rajiv Gandhi and then Sri Lankan President J R Jayewardene envisaged the devolution of powers to the provinces in the midst of the island's bitter ethnic conflict.
Also Read
Rajapaksa, who was in power from 2005-14, has been credited with crushing the LLTE's violent campaign for separate heartland in 2009.
The Tamil National Alliance (TNA), Sri Lanka's main Tamil party, had supported Sirisena in this month's elections after Rajapaksa failed to implement the 13th amendment.
Elaborating his government's 100-day programme, Wickremesinghe said introduction of democratic reforms would form a major part of it.
"We were a coalition of different political parties with different objectives. But we got together to end the dictatorial family rule," Wickremesinghe said.
In the same spirit, he said the new government welcomes proposals, ideas and criticism from all political parties.
"It is a challenge for all of us to get together in solving the national question," Wickremesinghe said.