Cord leader Raila Odinga on Sunday congratulated Gambian president Adama Barrow as he takes over office.
Barrow left the country after talks failed to persuade former President Yahya Jammeh to step down.
Nigeria's president flew to Banjul to try to broker a deal but Jammeh would not relinquish power.
But Jammeh on Saturday flew into exile in Equatorial Guinea after stepping down under pressure from West African nations to accept that he lost a December election.
"We congratulate the people of Gambia for their steadfastness in demanding change and for insisting that their choices be respected," Raila said in a statement.
Raila further praised Ecowas for standing with the people of Gambia and for democracy.
The African Union said it will no longer recognise Jammeh's rule beyond this point.
"The firm stand by Ecowas that has made it possible for the people of Gambia to get a leader of their choice is a significant step that resonates with the dreams and aspirations of Africans," Raila said.
Raila said the Continent should be a beacon of hope and not the death yard for democracy in the 21st Century.
"We look forward to strengthening our bonds with progressive forces both in Gambia and across the Continent to ensure prosperity, peace, and democratic traditions take firm roots in Africa," he said.
"I wish the President and the people of Gambia success as they embark on the gigantic task of rebuilding their country and reawakening its potential."
Ecowas, a 15-nation bloc of West African states that organised the delegation, had said it would consider removing Jammeh using military force if he refuses to step aside.