Siobhan Haughey won a consecutive medal in the women's 200m freestyle, earning bronze on top of the silver she won in Tokyo.

The Hong Kong star was among the first to turn at the half-way point before her Australian rivals Mollie O'Callaghan and Ariarne Titmus turned up the heat in the second 100 metres.

O'Callaghan pulled away from Titmus and Haughey in the last lap to win in an Olympic record time of 1 minute, 53.27 seconds, 0.54 seconds ahead of defending champion Titmus who settled for silver while Haughey picked up the bronze in a time of 1 minute, 54.55.

Haughey said after the race that her time wasn't as good as she thought it would be, but she's still satisfied with the result, saying the Australian swimmers were really strong.

She said it was a special moment for her because when she won silvers in Tokyo, there were no spectators because of Covid, and she's glad that her parents were among many in the crowd cheering her on.

The star swimmer also thanked Hongkongers for staying up to support her and other SAR athletes.

"Thank you so much for everyone who's been waking up really early to watch our races, our matches and competitions," she told reporters.

"I haven't really been on social media a lot these past few days, but I've received everyone's messages and all the love and support, so, thank you so much and please keep supporting us because it means the world to us."

This is Haughey's third Olympic medal following the two silvers she won in the 100m and 200m freestyle events at the Tokyo Games three years ago.

She is due to compete in the women's 100m free on Tuesday.