Hayley Elizabeth Atwell was born in London, England, to Allison Cain, a motivational speaker, and Grant Atwell, a photographer. Growing up in London, she was exposed to a diverse cultural environment that fostered her interest in the arts and performance. Her dual citizenship (British and American) provided her with opportunities that broadened her perspective from a young age.

Atwell honed her acting skills at the prestigious Guildhall School of Music and Drama in London. This period was crucial in developing her foundational acting techniques, stage presence, and versatility. Guildhall provided her with rigorous training in classical and contemporary theatre, preparing her for the diverse roles she would later undertake.

Atwell garnered significant attention for her role as Catherine Fedden in the BBC miniseries 'The Line of Beauty,' adapted from Alan Hollinghurst's novel. This project marked a turning point in her career, showcasing her ability to portray complex characters with nuance and depth. The series received critical acclaim, further solidifying her reputation as a rising talent.

Atwell starred as Julia Flyte in the film adaptation of Evelyn Waugh's 'Brideshead Revisited.' Her performance was widely praised, demonstrating her ability to handle period dramas with grace and emotional resonance. The film's success exposed her to a wider audience and cemented her status as a leading actress.

Atwell's career reached new heights when she was cast as Peggy Carter in 'Captain America: The First Avenger.' This role introduced her to a global audience and established her as a beloved character within the Marvel Cinematic Universe (MCU). Peggy Carter's intelligence, strength, and unwavering sense of justice resonated with fans, making her an iconic figure.

Atwell reprised her role as Peggy Carter in the ABC television series 'Agent Carter.' The series allowed her to further explore the character's backstory and adventures as a secret agent in post-World War II America. While the show was short-lived, it gained a dedicated following and solidified Peggy Carter's legacy as a strong female lead within the MCU. The series provided a platform for Atwell to showcase her action and dramatic range.

Atwell received an Olivier Award nomination for Best Actress for her performance in 'Rosmersholm' at the Duke of York's Theatre. This recognition highlighted her continued commitment to stage work and her ability to deliver powerful and captivating performances in classic theatrical productions. The nomination underscored her versatility as an actress capable of excelling in both screen and stage roles.

Atwell played the role of Grace in 'Mission: Impossible - Dead Reckoning Part One'. This action-packed film expanded her audience and offered a different type of role, demonstrating her action capabilities.