Sexton, who suffered a leg injury in the 32-19 win over France last month, missed the Six Nations leaders' victory over Italy.
He is in line to overtake compatriot Ronan O'Gara atop the Six Nations' all-time points scorer charts.
British & Irish Lion Furlong missed the opening three games with a calf injury, while Ringrose also returns after missing the trip to Italy.
Robbie Henshaw (29), Jamison Gibson Park (31) and Cian Healy (35), who are coming back from longer term injuries, are on the bench.
Conor Murray (33), who dropped to the bench for the win over Italy, has been named to the starting line-up.
Sunday's game will also serve as a preview for this year's World Cup in France, with Ireland and Scotland having been drawn in the same pool as South Africa, Tonga and Romania for the tournament.
Meanwhile, lock Jonny Gray and number eight Jack Dempsey have been drafted into the Scotland team as fullback Stuart Hogg becomes the fourth player to reach 100 caps for the side.
Coach Gregor Townsend has made two changes from the team that lost 32-21 in France last time out, with Gray to partner his brother Richie in the second row as Grant Gilchrist misses out through suspension.
Dempsey earns a first start of the championship at the back of the scrum as captain Jamie Ritchie moves to openside flanker and Matt Fagerson is on the blindside.
The front row comprises hooker George Turner, who will have props Pierre Schoeman and Zander Fagerson either side of him.
The backline remains unchanged for the fourth game in a row as Hogg reaches his century of caps having made his debut in 2012.
Only former hooker Ross Ford (110 caps), fullback Chris Paterson (109) and wing Sean Lamont (105) are ahead of Hogg on the all-time list.
Ireland, who top the standings on 15 points after three matches, will hope to still be in line for a grand slam when they host England a week later in their final game.
Scotland are second with 10, ahead of England and France on points difference.
England host France on Saturday.
