The actress, 46, was all smiles as she posed for photographers outside of the Regal Cinemas L.A. LIVE Stadium 14 in Los Angeles for the premiere of her new action film, Peppermint — which stars Garner as a self-made killer set to avenge the brutal murders of her husband and daughter.

She looked chic in a short, one-shoulder little black dress with a long train. Garner accessorized the ensemble with diamond jewelry and coordinating strappy, sparkling sandals. She wore her hair down in light beach waves, and kept her makeup all natural with a glossy pink lip.

Garner appeared to be having fun too, sneaking away to sign some autographs for eager fans waiting outside.

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Nearly a week earlier, Garner was photographed in a very different situation: driving her ex Ben Affleck, 46, to a treatment facility in Malibu on Aug. 22.

A source told PEOPLE at the time that Garner’s decision to intervene and take Affleck to rehab was built around her concern for the three children they share — son Samuel Garner, 6, and daughters Seraphina Rose Elizabeth, 9½, and Violet Anne, 12.

“Her number one concern is the kids,” the source said.

Garner’s kids were by her side on Aug. 20 when she received the honor of a star on the Hollywood Walk of Fame.

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Peppermint marks the actress’ return to action, a genre she first made her name in as the star of ABC’s hit series, Alias. She hasn’t had a leading role in an action film since playing Elektra in 2003’s Daredevil.

Part of that absence can be attributed to taking on the role of mom. “I had done so much action and then I started having babies. It’s hard on your body,” she told Extra. “So I was pregnant. I was nursing. I was recovering from those things and it took a long time.”

Motherhood also made Garner picky when choosing roles. “I would have to decide, ‘No I actually do love this job,’ ” Garner told Variety, explaining that she took a six-month break from work after the birth of her third child in 2012 because “three kids just knocks you flat on your ass.”

It was a phone call from her then-agent of 20 years Patrick Whitesell, however, that made her rethink her career.

“Patrick said, ‘Either this is the telephone call about you doing Dallas Buyers Club and how we’re going to make that happen, or it’s a telephone call about your retirement,’ ” Garner recalled to Variety. “That was a real moment of decision and clarity and I loved him for it because it forced me to say, ‘Okay, I am not ready to be home all the time.’ ”

These days, Garner has starred in a string of hit movies like Love, Simon and the Tribes of Palos Verdes.

But despite her regular onscreen presence, her little ones’ perception of the star remains unchanged. “They just want me to come home and be mom,” Garner told Extra.

Peppermint hits theaters September 7.