Michael D.Higgins, a former culture minister and part-time poet from Ireland's junior coalition party, will be named the country's new president later on Saturday after a final vote count is completed.
Higgins, 70, a mainstay of human rights demonstrations for decades, was assured of victory over a reality TV star and an ex-IRA commander on Friday when all his rivals conceded defeat before the first round of votes were counted.
The Labour candidates' win will be a relief for the government after senior partners Fine Gael posted their worst presidential performance while ex-guerrilla fighter Martin McGuinness's Sinn Fein opposition party made further gains.
Higgins, whose statesman-like poise stood him in good stead during a grubby campaign full of personal mud-slinging, won 40 percent of first preference votes putting him 11 percentage points clear of nearest rival, businessman Sean Gallagher.
McGuinness was in third place after the first round of counting with 14 percent, more than double Fine Gael's showing and an improvement on the record 10 percent of votes Sinn Fein secured in February's election.
Buoyed by public anger over an economic crisis that led to an EU/IMF bailout last year, Sinn Fein is trying to move into the political mainstream in the Republic of Ireland after already doing so in Northern Ireland where they share power.
Higgins' election will be confirmed at around 1600 GMT once the distribution of second preference votes from lower-placed candidates push him over the required threshold.
Establishing a final result in national polls in Ireland is a slow process due to a complicated electoral system and manual counting.
The votes on two referendums on whether to allow the government to cut the pay of judges and boost the power of parliamentary committees still have to be calculated and counting will commence after the presidential result.
Higgins' Labour party also won a 38th parliamentary seat in Dublin late on Friday, becoming the first ruling party to win a by-election since 1982 and reinforcing the government's already large lower-house majority.
(Reporting by Padraic Halpin; Editing by Sophie Hares)