Powrie won gold with Jo Aleh in the women's 470 class at London and silver in Rio, with the pair also crowned world champions in 2013. In addition, they won three silver medals at world championships.
"Jo and I have been sailing together for eight years and achieved possibly everything we could have," Powrie said in a statement.
"I had to ask the question, 'was I excited about going again and did I still feel like there was a challenge to achieve?'
"I also had to take family into consideration and decided it was time to move on and experience different things and challenge myself in different ways."
Aleh said last week she was taking a year off from sailing the dinghy but was still keen on going through to the 2020 Games in Tokyo.
She recently completed the Sydney to Hobart Yacht Race and was keen to crew on a boat in the round the world Volvo Ocean Race later this year.
"I had a great eight years with Polly," Aleh said. "I know her so well, so it's a bit sad it's over but I support whatever she wants to do.
"I'm fully open to the idea of putting another campaign together for the Tokyo Olympics and I had planned to do it with Polly but I want to do some other things in the meantime to keep me interested."
(Reporting by Greg Stutchbury; Editing by Ian Chadband)
