The 35-year-old actress wore a V-neck white shirt with a blue-striped multilevel skirt that read, 'It's always summer somewhere,' with patches of bananas, animals and other seasonal emblems.
The 5ft7 beauty wore brown sunglasses and white sneakers with her dark brown tresses in bangs and a minimal makeup. She had an over-the-shoulder handbag and carried a black tote bag.
'I feel like I've seen it all, read it all and this book consistently shocked me,' said Biel. 'I loved the material and became a huge fan of it.'
The veteran actress, who's also a producer on the miniseries, said she had to tap deep into her psyche to effectively portray the mom-turned-murderer.
'Every character I play I try to find the connection point. Even if it's a villain or someone like Cora, there's a cornerstone of something I grab onto,' she said. 'So in this experience I connected with this very humanistic idea that we are all capable of violence and I can relate to that feeling of wanting to be aggressive in some way at different points of my life.'
The mom-of-one celebrated her fifth wedding anniversary with pop superstar Justin Timberlake earlier this year. She said she understood certain aspects of her character 'as a mother and a wife,' adding, 'I empathized and related to her at the same time as I was horrified and terrified of her.'
The Sinner, which also features Bill Pullman and Christopher Abbott, airs Wednesdays on USA at 10/9c.