She finished ranked third in the competition for intercepts (26) and ranked in the top 10 for deflections (42) and gains (26).
"I'm pretty shocked to be honest and a bit lost for words," Guthrie said.
"I definitely wouldn't have been given this award without the Mystics, they've made me feel like part of the group and under them I've been able to flourish and play the game I want to play out there."
"Being around these awesome athletes made me want to improve and get better and try and find the real consistency in my game," she said.
Guthrie is the first midcourt player to win the best new talent award since it was introduced in 2010 and follows previous winners Mwai Kumwenda (2014), Jhaniele Fowler-Reid (2013), Julianna Naoupu (2012), Kayla Cullen (2011) and Sharni Layton (2010).
The ANZ Championship finals series gets underway tomorrow night with the NSW Swifts hosting West Coast Fever in the Australian conference elimination final in Sydney. In the New Zealand elimination final, the Magic will host the Steel in Hamilton on Saturday afternoon.