Nicholls has played 45 games since joining the club as a 17-year-old access selection in 2010, while Leslie has played six games, after being recruited with pick No.20 in the 2013 National Draft.
“I believe we have the best group of boys, and the best city to play footy in, so I couldn’t see myself going anywhere else in 2017,” Nicholls said.
“The coaches and the leadership group have been awesome in terms of culture and giving the guys a license to lead.”
Leslie also said he is delighted to have re-signed with the Suns.
“I couldn’t be happier to be continuing my AFL career in Queensland and I can’t wait to get back into it,” Leslie.
“The off-season provides everyone the opportunity to refresh and recharge, but our sights are firmly fixed on continuing to build confidence and momentum when we return for pre-season training.”