Hannah Waddingham was born on 1974, in Wandsworth, London. Her family was involved in performing arts as her mother, Melodie Kelly, and both her maternal grandparents were opera singers.

She is best known for her contribution to West End musical theatre, particularly her performances in the original London production of "Spamalot" as the Lady of the Lake and as Desiree Armfelt in Trevor Nunn's acclaimed revival of "A Little Night Music", roles that earned her two Olivier Award nomination.

In October 2000, she released the single "Our Kind of Love", billed simply as Hannah, in the UK Singles Chart where it peaked at No. 41.

In 2008, she made her film debut as Elizabeth Maddox in How to Lose Friends & Alienate People (2008). Her other film credits include Into the Woods (2011), Les Misérables (2012), Winter Ridge (2018) and The Hustle (2019).

In 2015, Waddingham joined the cast of the fifth season of the HBO series Game of Thrones (2011) as Septa Unella. Hannah appeared in Sex Education (2019) as Sofia Marchetti. In 2020, she gained international recognition for her acclaimed portrayal of Rebecca Welton in the Apple+ comedy series Ted Lasso (2020), for which she won Best Supporting Actress in a Comedy Series at the 2021 Critics Choice Awards.

For about a decade she's been with her partner, Gianluca Cugnetto. In 2014, the couple welcomed their first child.