August 16, 2021 | 10:42am

This isn’t your grandma’s cardigan.

Megan Fox stepped out in Los Angeles over the weekend, putting a typically sexy spin on an ordinarily conservative closet classic.

The “Transformers” actress, 35, looked red-hot in a crimson Jacquemus cardigan ($410) that, while held closed with a delicate gold logo charm in lieu of a button, fit right in with this summer’s skin-baring single-button trend.

Fox skipped a shirt underneath the sweater, pairing the knit with a matching pencil skirt ($605) featuring sultry waist cutouts. She finished her flame-hued outfit with a red Mietis mini bag ($660 and Femme LA stilettos ($189).

Megan Fox put a sexy spin on the cardigan while out in LA.
Megan Fox put a sexy spin on the cardigan while out in LA.
London Entertainment/Shutterstock
Megan Fox
The star’s Jacquemus top has also been spotted on Hailey Baldwin, Kendall Jenner and Bella Hadid.
London Entertainment/Shutterstock

The look was somewhat reminiscent of the similarly scarlet getup Fox chose for her birthday dinner date with boyfriend Machine Gun Kelly in May, comprised of a cherry Alex Perry pantsuit styled with a matching bra rather than a shirt.

Megan Fox celebrated her 35th birthday in a sexy red suit and bra, with Machine Gun Kelly wearing a matching outfit.
Megan Fox celebrated her 35th birthday in a sexy red suit and bra, with Machine Gun Kelly wearing a matching outfit.
Splash News

The brunette bombshell is famously fond of itty-bitty tops, having been snapped in everything from a long-sleeved underwire look to a soft ribbed bralette — the latter paired, incidentally, with a coordinating cardigan.

No word on what “Cardigan” songstress Taylor Swift thinks of Fox’s take on her favorite knit.

Megan Fox wore an Urban Outfitters cardigan-and-bra combo in April.
Megan Fox wore an Urban Outfitters cardigan-and-bra combo in April.
WireImage