One of the finest allrounders in the world, New Zealander Kerr will join Sixers this summer under new rules that allow each club to sign one player outside of the overseas draft.

Kerr has been with the Heat since 2019, and has won the club's player-of-the-year award three times.

She is the No. 2 ranked allrounder in the world, and is one of the best spinners in the global game with 62 wickets at an economy rate of 6.42 in 58 matches for the Heat.

Ultimately, the 23-year-old was won over by having close family in Sydney, with her sister Jess having played for Sixers last season.

"It was an extremely hard decision to leave Brisbane as the players and staff there have been nothing but good to me," Kerr said. "With the scheduling of women's cricket there is not much downtime and being based in Sydney was a big part of my decision.

"I have close family living in Sydney which will help make the time away from home a lot of fun. I want to keep finding ways to better myself as a cricketer and a person so I'm looking forward to this exciting new opportunity with the Sixers."

Heat confirmed on Tuesday they attempted to retain Kerr under the pre-draft multi-year contract system.

"The Heat were keen to retain Melie and put a competitive offer to her," Queensland's head of cricket Joe Dawes said.  "However we understand that being near to family is important in this stage of her life, so a move to Sydney where we know she has close family made sense for that reason.

"Our fans around the country will no doubt be very disappointed not to see her out on the field playing for Brisbane again this summer.

"But we thank her and her family for trusting us back when she signed her first contract to play in the WBBL and certainly wish her all the best as she takes on a new challenge."