Garner and 43-year-old Affleck, who have three children, announced they were divorcing on June 30. They got married in 2005.
She attended the "Think It Up" telethon at Barker Hangar in Santa Monica, California on Friday, September 11.
The 43-year-old actress was decked out in a "Think It Up" t-shirt and dark jeans, reported Aceshowbiz.
She did not wear her wedding ring.
She was all smiles as she mingled with the likes of Jessica Biel, Halle Berry, Gwyneth Paltrow, Jeremy Renner, Seth Meyers, Joe Manganiello, Terry Crews, will.I.Am, Julie Chen, Kristen Bell, Jason Bateman, Eric Stonestreet, and J.K. Simmons for the good cause.