The move follows Sinclair's recent departure from Kelly Racing, where he was team manager, after six years at Braeside.
Supercars announced the 37-year-old's election to the Commission via its official website, where Sinclair stated, “I decided that I wanted to pursue some new challenges and look outside the sport a little bit.
“It's obviously a pretty exciting time with Kelly Racing (switching to Mustangs) but I was committed with my family to take a step back off the tour and invest a bit more time at home.
“This is a good opportunity for me to stay invested in Supercars, which has been my lifeblood, and give something back at a time where I'm taking on some new challenges and learning some new things.”
Sinclair, who won the championship as James Courtney's engineer at Dick Johnson Racing in 2010, is not the only new arrival to the Commission.