The 31-year-old will join former Rebels team-mates Jodi Brown (nee Te Huna), Phillipa Finch, Anna Thompson and Kahurangi Waititi.
The wiry goal attack made 32 appearances for the Rebels, landing 558 of her 787 attempts on goal (71%), and played five tests for the Silver Ferns.
She hung up her bib last year but has been coaxed back to play for the Tactix while on maternity leave from her teaching job at Waitaki Girls High School.
Mitchell gave birth to her first child, Amelia, earlier this year.
"It is a decision I've made in the last week," Mitchell explained.
"I've got an opportunity because I'm on maternity leave until the middle of next year . . . so it has worked out quite nicely."
Mitchell grew up in Mid-Canterbury and played club netball in Christchurch alongside Tactix coach Helen Mahon-Stroud.
She played for the Canterbury Flames from 1998 to 2002 before joining the Rebels.
Mitchell, who has kept herself fit playing club netball in Oamaru, said she should not have too much trouble fitting back in with so many former team-mates in the side.
Mitchell and Brown were the shooting combination for the Rebels in 2007 and Thompson and Finch played in the mid-court.
Waititi played alongside Mitchell at the Rebels in 2006.
Canterbury and Silver Ferns wing attack Maree Bowden also has Otago connections having played for Otago.
The Tactix will play the Southern Steel at the Edgar Centre in Dunedin on April 19. With just one Dunedin-based player in Katrina Grant in the so-called home side, the Tactix may well enjoy some vocal support from the crowd.
Meanwhile, the Steel is appealing to the eligibility committee in an attempt to include an Australian player in its roster to replace Jenny May-Coffin, out because of work commitments.
Last month, its application to include former Australian international Megan Dehn was declined.
Dehn has since been included in the Queensland Firebirds squad.
