Lisburn boxer Kurt Walker will begin his Olympic medal bid against Quiles Brotons while siblings Michaela and Aidan Walsh have byes into the last 16.
Flyweight Brendan Irvine, Ireland's joint flag-carrier, will begin his competition against Carlos Paalam at 00:03 BST on Monday morning.
Walker takes on Spaniard Brotons in the last 32 on Saturday at 04:03 BST.
Michaela Walsh will make her Olympic debut on Monday (06:27) in the last 16 of the women's featherweight division.
Her brother Aidan, competing in the men's Welterweight division, starts on Tuesday at 03:30 BST.
The 24-year-old from Belfast, who won silver at the 2018 Commonwealth Games, booked his spot in the Ireland team through the European qualifiers.
Michaela is four years older and won silver at the Commonwealth Games in 2014 and 2018.
Boxing captain Irvine, who will carry the Irish flag alongside Kellie Harrington in Friday's opening ceremony, meets Filipino Paalam in what is his second Olympics.
Walker, 26, earned a Tokyo berth courtesy of his world ranking having lost an Olympic qualifier in London,
He won a gold at the 2019 European Games in Minsk and silver at the 2018 Commonwealth Games.