Jessica Biel unveiled a dramatic hair transformation - from chest-length locks to a short bob - on Saturday evening.

The 42-year-old Emmy nominee - who boasts 19.4M social media followers - captioned her before/after video: 'Brought back the f*** a** bob.'

Jessica - who previously had a bob in 1998 and 2006 - enlisted Milbon global creative director Anh Co Tran to cut of her long signature mane.

Earlier that same afternoon, Biel stopped by independent bookstore Annabelle's Book Club LA in Studio City to attend an hour-and-a-half-long book signing event.

The former Cruel Summer producer wore a seafoam-colored blouse, blue jeans, and white pumps to promote her 64-page literary debut A Kids Book About Periods, which hit shelves last Tuesday.

Jessica Biel unveiled a dramatic hair transformation - from chest-length locks to a short bob - on Saturday evening

Jessica is mother to two sons - Silas, 9; and Phineas, 3 - and she is impressed with how well her eldest child reacted to her menstruation manual created for children aged 7-9.

'He kind of was like, "Oh, that's weird." I said, "Yeah, it is kind of weird, but trust me, it's weird for me too. When it happens to me, it's still weird,"' Biel recalled to People last Friday.

'And I said, "Think about it. There's somebody at school that might have their period and they might need your help or support someday, and it's really going to be important for you to understand what's happening so you can help a friend if they need something."'

The Minnesota-born beauty continued: 'I got a piece of it in, but I could see the wheels in his brain kind of turning over, and he was so cool about it. I was like, "Oh my God, score! We did it!" That was the first step in much bigger conversations and deeper conversations that I hope to have with him. And that's exactly why I wrote this book.'

For every book sold, Jessica will donate 5% of the proceeds to PERIOD, a non-profit organization that 'strives to eradicate period poverty and stigma through service, education, and advocacy.'

Biel's husband of 11 years - 10-time Grammy winner Justin Timberlake - performed a two-stand at Kia Forum in Inglewood, CA on Friday and Saturday.

The 43-year-old pop star - whose 2023 was plagued with bad PR - is next scheduled to bring his 77-date The Forget Tomorrow World Tour to Arizona's Footprint Center in Phoenix this Tuesday, and his seventh headlining tour runs through December 16.

The two-time Golden Globe nominee originally met Justin in 2007 while snowboarding with a group of friends in Park City, UT.

The 42-year-old Emmy nominee - who boasts 19.4M social media followers - captioned her before/after video: 'Brought back the f*** a** bob'

Jessica - who previously had a bob in 1998 and 2006 - enlisted Milbon global creative director Anh Co Tran to cut of her long signature mane

Earlier that same afternoon, Biel stopped by independent bookstore Annabelle's Book Club LA in Studio City to attend an hour-and-a-half-long book signing event

The former Cruel Summer producer wore a seafoam-colored blouse, blue jeans, and white pumps to promote her 64-page literary debut A Kids Book About Periods, which hit shelves last Tuesday

Jessica is mother to two sons - Silas, 9; and Phineas, 3 (pictured April 30) - and she is impressed with how well her eldest child reacted to her menstruation manual created for children aged 7-9

Biel recalled to People last Friday: 'He kind of was like, "Oh, that's weird." I said, "Yeah, it is kind of weird, but trust me, it's weird for me too. When it happens to me, it's still weird"'

The Minnesota-born beauty continued: 'And I said, "Think about it. There's somebody at school that might have their period and they might need your help or support someday, and it's really going to be important for you to understand what's happening so you can help a friend if they need something"'

Jessica added: 'I got a piece of it in, but I could see the wheels in his brain kind of turning over, and he was so cool about it. I was like, "Oh my God, score! We did it!" That was the first step in much bigger conversations and deeper conversations that I hope to have with him. And that's exactly why I wrote this book'

For every book sold, Biel will donate 5% of the proceeds to PERIOD, a non-profit organization that 'strives to eradicate period poverty and stigma through service, education, and advocacy'

The two-time Golden Globe nominee's husband of 11 years - 10-time Grammy winner Justin Timberlake (L, pictured April 30) - performed a two-stand at Kia Forum in Inglewood, CA on Friday and Saturday.

The 43-year-old pop star - whose 2023 was plagued with bad PR - is next scheduled to bring his 77-date The Forget Tomorrow World Tour to Arizona's Footprint Center in Phoenix this Tuesday, and his seventh headlining tour runs through December 16 (pictured Saturday)

Last Wednesday, Jessica signed on to executive produce and narrate Investigation Discovery's true-crime docu-series Fatal Destination, which will air next year

Last Wednesday, Jessica signed on to executive produce and narrate Investigation Discovery's true-crime docu-series Fatal Destination, which will air next year.

On May 1, Biel signed on to co-star with Elizabeth Banks as polar-opposite siblings in Olivia Milch and Regina Corrado's thriller series The Better Sister for Prime Video, which is based on Alafair Burke's 2019 novel.

In March, Peacock picked up The Good Daughter, a limited series psychological suspense thriller based on Karin Slaughter's 2017 novel, which the Iron Ocean Productions co-founder will executive produce and star as a lawyer called Charlotte.

And in February, Jessica signed on to star as real-life trailblazing mountain climber Beryl Knauth in Kyle Marvin's 1970 Yosemite-set drama Batso alongside Ethan Hawke and Daniel Radcliffe.

And with the presidential race looming, Biel might very well be supporting independent candidate Robert F. Kennedy Jr., with whom she lobbied against a California vaccination bill limiting medical exemptions back in 2019.