Antonis Samaras, the leader of the New Democracy party, which won Sunday’s election, has been sworn in as the country’s new Prime Minister.
Mr Samaras took the oath at a Greek Orthodox ceremony in Athens.
Afterwards he pledged his government would “do whatever we can for the people to come out of this crisis”.
“Tomorrow I will ask for the new government to be formed – [we will] work hard so we can give hope to our people,” Mr Samaras said.
The coalition deal follows weeks of uncertainty, after parties failed to agree a government on the results of an election on 6 May.
Syriza – the party which came second in Sunday’s poll – will be a defiant voice of opposition, correspondents say.