"My family first learned about Hollie's story a couple of years ago through the cricket community and I have always been struck by the Beattie family's perseverance, strength and positive attitude. Since hearing that Hollie required more treatment I have been trying to find a way to support in some small way," Southee wrote in the auction's description.
"I am hopeful that this shirt can help contribute in someway to the Beattie family's ongoing medical needs as Hollie continues to fight. As a parent my heart goes out to them as they battle on.
"The Beattie family's strength serves as a great reminder that whatever we may go through on the cricket field with success and failure it's nothing compared to the challenges faced by those suffering with their health like Hollie."
So far the shirt has reached a bid of $43,300 with over six days left to run in the auction.
On Thursday, the Beattie family posted an update on their Facebook page relaying how much Southee's efforts had already impacted their cause.
"Much more quickly than anticipated, thanks to Tim Southee's incredible auction, we have also hit our second $50k milestone today, so that ticks off the payment of Hollie's next round of treatment.
"Thank you awesome people and especially Tim and the Black Caps for coming up with such a fab idea."
Hollie is currently in Spain undergoing radioimmunotherapy that is administered through a port in her skull.
The family has previously stated that if, for some reason, it raises more money than is needed, or the money can not be used, it would be given to another child in need.