Walters (23) has ridden 71 winners in his career but has taken a step back from race riding after battling weight problems.
The position at Richards' stable will provide a steady income, Walters said.
''I wanted a fulltime job. It's a guaranteed wage every week,'' he said.
''With the way my weight was, I lost interest in the wasting every week to get down to a certain weight.
''I was in the 60s - 61kg or 62kg - I had to get down to 57kg every meeting so it made things difficult for me.''
The move south also allows Walters to be near his partner, apprentice jockey Toni Direen.
''It will be better to be close to her.''
Walters has not completely ruled out a return to race day riding, but has told Richards he plans to focus on the stable position.
''I still want to go over the jumps at some stage.''
Later on, I'll come back to the flat - but I did four or five years of it as my apprenticeship and in my last year I've got lazy.''
Walters picked King Montrose as his favourite horse to ride.
He won four races on the Neill Ridley-trained galloper - two open sprints, a rating 85 mile and the 2011 Dunedin Gold Cup Trial over 2000m.
Walters is known for a quick wit, and he was quick to capitalise on Richards' double success at Oamaru on Sunday.
''I see Paul has trained two winners today. I haven't even started and I've already lifted the team,'' he joked.
