The opening ceremony aimed to deliver a message of unity, while acknowledging the event is taking place amidst a global pandemic.
There were fireworks and a lighting display by drones before tennis superstar Naomi Osaka lit the Olympic flame.
Boxers Kellie Harrington and Brendan Irvine carried the Ireland flag into the Olympic Stadium.
Ronnie Delaney won a gold medal for Ireland at the Melbourne games in 1956.
He says Ireland's team this year is immense:
"I think it's going to be a great Olympic Games, because of the background to leading up to it. I think the Irish team is immense: 116 athletes, a tremendous number of teams, two teams - I'm delighted with that - hockey and rugby. I'd be thrilled watching hockey. I used to play very ordinary hockey, and I know a number of the young ladies who are taking part."
