Webb joined NSW Police in 1987 and previously was responsible for traffic and highway patrol and public transport.[3] She joined the Castle Hill Police Station, in the 1990s at a time when 10% of police officers were women, and grew to 35% as at 2021.[7] She later stated in 2021 that she "look[s] forward to growing our diversity and inclusion in the organisation".[7] Webb was the first woman to lead Traffic and Highway Patrol, since 2020.[3] She was promoted in 2017 to assistant commissioner, and subsequently moved to deputy commissioner in July 2021.[3] She has been a Board Member of NSW Police Legacy since 2018, and Vice-Patron since 2022.[8]
On 1 February 2022, Webb was formally appointed as Commissioner of the New South Wales Police Force.[2] Previous police commissioner ceremonies were traditionally held at Government House in Sydney, but Webb chose to accept her appointment in her alma mater at Boorowa Central School.[6]