Swimming at the 2020 Summer Olympics – Women's 4 × 100 metre freestyle relay

Returning from their triumph five years earlier in Rio, the experienced trio of Emma McKeon and sisters Bronte and Cate Campbell joined with the youngster Meg Harris to win Australia's third consecutive Olympic title in dominating fashion. Bronte led off the quartet in 53.01 before handing over to Harris (53.09). Holding a marginal gap over the field, McKeon blasted a 51.35 split - the quickest in the field and fifth-fastest of all time - to give the Australians a monstrous lead of over two seconds. As she did in Rio, Cate (52.24) anchored Australia home to win gold in a world record of 3:29.69. Moreover, the Australians' victory margin of 3.09 seconds was the largest in the event since the U.S. won by 3.22 seconds in 2000.

Canada's Kayla Sanchez (53.42) and Maggie Mac Neil (53.47) handed the third-leg duties to Rebecca Smith (53.63), who moved the Canadians from fifth to fourth but still 0.67 seconds behind the pace of the Americans. However, in a thrilling duel between the 100 m freestyle defending champions Penny Oleksiak and Simone Manuel, Canada's Oleksiak split 52.26 to overtake the U.S.' Manuel (52.96) and secure Canada a surprise silver medal in 3:32.78 - their best finish in the event after three previous bronze-medal feats (1968, 1976, 2016). While Erika Brown's 54.02 lead-off had the U.S. in sixth, the remaining legs from Abbey Weitzeil (52.68), Natalie Hinds (53.15) and Manuel helped the U.S. to recover and win bronze in 3:32.81, just 0.03 seconds behind Canada.

Winners in 2008, the Netherlands (3:33.70) fell short of the podium to come fourth despite valiant efforts from the 2012 100 m freestyle champion Ranomi Kromowidjojo (52.87) and Femke Heemskerk (52.05), who had the second fastest split in the field behind McKeon. Great Britain (3:33.96) edged out Sweden (3:34.69), who were led off in an Olympic record of 52.69 by superstar Sarah Sjöström, for fifth place. China (3:34.76) and Denmark (3:35.70) rounded out the championship field.

Prior to this competition, the existing world and Olympic records were as follows.

The following records were established during the competition:

The top 12 teams in this event at the 2019 World Aquatics Championships qualified for the Olympics. An additional 4 teams will qualify through having the fastest times at approved qualifying events during the qualifying period (1 March 2019 to 30 May 2020).^[5]

The competition consists of two rounds: heats and a final. The relay teams with the best 8 times in the heats advance to the final. Swim-offs are used as necessary to break ties for advancement to the next round.^[6]

All times are Japan Standard Time (UTC+9)^[1]

The relay teams with the top 8 times, regardless of heat, advance to the final.^[7]

^[8]