Counting still continued as Navinchandra Ramgoolam announced he was stepping down, and as opposition leader and ex-president Anerood Jugnauth declared he was the next prime minister in the Indian Ocean island nation.
"I will become the next prime minister," 84-year-old ex-premier Jugnauth said in a victory speech broadcast on national television, standing alongside other smiling leaders of his centre-right Alliance Lepep coalition.
"As promised, I will do everything so that there is a second economic miracle in the country," Jugnauth told the nation. He was previously prime minster between 1982-1995 and again between 2000-2003.
Jugnauth said he had won as voters had "felt the danger" of the change.
Ramgoolam, who had wanted to run for the presidency had he won but in a crushing defeat lost even his own parliamentary seat he had held since 1991, said the "elections were carried out with respect to democracy."
"The electorate has made its choice, I humbly accept its decision, and I will now meet the President of the Republic to submit my resignation," Ramgoolam said on national radio, speaking in Mauritius' Creole language.
The PTR-MMM coalition had agreed that if they won they would try to amend the constitution so the president would be directly elected. The role is a largely ceremonial position elected by parliament.
Jugnauth's Lepep fiercely opposed the proposed constitutional reform.
Out of a total of 62 parliamentary seats, by 1730 GMT official results declared 29 had been won by Lepep, compared to 10 for Ramgoolam's coalition.
Mauritian media projected that final results could see Lepep take some 45 seats, against 15 for its rival PTR-MMM, with two others going to local parties on the small island of Rodrigues, some 560 kilometres to the east.