The Dublin Rathdown constituency claimed a major scalp when Transport Minister Shane Ross lost the seat he had won in 2016 by topping the poll.
This constituency is renowned for major upsets, previously claiming Alan Shatter, Alex White and Liz O'Donnell.
Mr Ross was gracious in defeat, and congratulated Sinn Fein on its election success.
"I don't think tonight is a time for regret," he said.
"It's a time to congratulate those who are successful. There's obviously been a huge appetite for change. Those who represented that very articulately have been successful.
"I hope they make up a really successful government and they bring about the changes which are necessary.
"I'd be fairly sanguine about it, when you get a democratic vote of this sort it's the wish of the people, and if I made mistakes and could have done things differently that's alright. I did what I thought was right all the time and I'm happy to give others the opportunity to do what's right."
Meanwhile, another outgoing Independent minister - Katherine Zappone - is in serious trouble in Dublin South-West as she received 5.5pc of votes on the first count.
Sinn Fein's Sean Crowe topped the polls with nearly 30pc and was elected on the first count with 20,072 votes.
However, Ms Zappone - who served as Children's Minister - is set to lose her seat and will be hoping for transfer votes to bring her over the quota of 11,261, having received 3,708 - far lower than her votes in 2016, when she totalled 4,463 on the first count, 6.6pc.
The minister attended the count centre yesterday morning but had left by midday.
A second count last night brought her up to 4,141 votes.
Meanwhile, Labour will not enter talks to form the next government after what leader Brendan Howlin described as a "bad day" for the party with former tanaiste and party leader Joan Burton losing her seat.
Ms Burton was out of the running early on in Dublin West amid a surge toward Sinn Fein and the party's Limerick City TD Jan O'Sullivan was also struggling to hold her seat.
However, Labour will be boosted by the expected return of senator Aodhan O Riordain in Dublin Bay North and senator Ged Nash in Louth.
Labour was also on course to hold seats in Cork East, through Sean Sherlock, and Tipperary through former deputy leader Alan Kelly.
In Dublin Fingal, Duncan Smith could hold the seat vacated by the retiring Brendan Ryan. The party was also hopeful councillor Mark Wall could regain Kildare South, held by his father Jack.
Mr Howlin, who is set to hold his seat in Wexford, all but ruled out going into government, with sources saying the party does not have a mandate to do so.
Meanwhile, the Social Democrats hoped to more than double their number of Dail seats, with co-leaders Catherine Murphy and Roisin Shortall holding Kildare North and Dublin North-West respectively.
Last night, the party was confident that Gary Gannon would take a seat in Dublin Central, with Cian O'Callaghan on course in Dublin Bay North.
Jennifer Whitmore was also in contention for a seat in Wicklow.
Ms Shortall said she had not spoken to Sinn Fein leader Mary Lou McDonald, but would be speaking to "all parties".
"Today we are concentrating on just our own numbers and hoping that we will maximise the number of TDs," Ms Shortall said.