The Auckland connection came through Sussex players, Chris Nash, Craig Cachopa and Luke Wright, all of whom have spent time playing for Auckland.
Indeed Cachopa is heading back too, and may figure in Auckland's plans this season.
Mills is seriously fast, took 15 wickets at 19.7 with a strike rate of a wicket every 15 balls in this year's English domestic competition.
He played one T20 international against Sri Lanka this year and his overall record in the shortest form, 41 wickets in 35 bams at 21.41, is appealing too.
"He's different," Auckland coach Mark O'Donnell said, adding he had been impressed by the feedback he'd got from players who have played with and against Mlls.
"It is exciting. If you come up with someone who no one has seen or faced, it does take a few balls to have a look. I'm really looking forward to it."
O'Donnell pointed out that with the proliferation of T20 leagues around the world "you can make a good living out of it. T20 has serious skills which people didn't originally pick up".
Mills confirmed it's just T20 for the next couple of years and "I've just turned 24
so hopefully have quite a few years left in me".