The Economic Community of West African States said Vaz had nominated Aristide Gomes as “prime minister of consensus” after consultations with political actors and civil society.
“This nomination will be taken by presidential decree on April 17, 2018 in Bissau,” it added in a final communique after the closed-door talks in Togo’s capital, Lome.
Gomes previously served as prime minister of the former Portuguese colony from 2005 to 2007.
Parliament would resume on April 19 and Vaz also announced that parliamentary elections would be held on November 18, 2018.
Togo’s President Faure Gnassingbe, who holds the rotating presidency of ECOWAS, and nine other regional heads of state met in extraordinary session to try to end the impasse.
Guinea-Bissau has been in the grip of a power struggle since August 2015, when President Vaz sacked his then prime minister Domingos Simoes Pereira.
Vaz has since nominated several prime ministers but he has failed to gain the support of political parties.
ECOWAS has stipulated a consensus candidate who has the president’s trust was needed to be a new head of government, and stay in the post until the next elections.
An ECOWAS delegation was in Bissau on Wednesday to meet Vaz and key parties in the dispute.
Regional leaders said they “noted these decisions and dates which will be part of the roadmap” and called on “all actors to work together to bring stability to the country”.