Bronze, who left Barcelona last month after her contact expired, has won the Women's Champions League five times, twice with Barca and three times with French side Lyon.
She will be reunited with manager Sonia Bompastor and Camille Abily, who moved to Chelsea from Lyon following the departure of longtime coach Emma Hayes.
"I know both Sonia and Cammy really well from my time at Lyon," said Bronze, who has signed a two-year contract with Chelsea.
"So naturally that was a factor in coming. It’s a new era as well that I want to be part of. Emma (Hayes) obviously was amazing for this club and took it to a high level. But those two are another big reason for wanting to come here.
"To be at a club like Chelsea that is renowned for winning trophies, it's a perfect match-up. That's what I've enjoyed the most in my career. I’m so excited to get going."
Bronze also won two LaLiga F titles, a Copa de la Reina and two Spanish Super Cups with Barcelona. She won EURO 2022 with the Lionesses and has 124 caps for England.
"Lucy will bring leadership to the group. She is a serial winner and a versatile defender. She has lots of experience and a winning mentality which we feel will fit well into the squad," Chelsea's general manager Paul Green said.
Chelsea won the WSL title for a fifth year in a row last season, finishing ahead of Manchester City on goal difference.
