Williams joined "BBC Breakfast" on 12 January 2001 as a relief presenter, initially presenting on Friday–Sunday alongside Darren Jordon, to cover for main presenter, Sarah Montague, and then later with Jeremy Bowen, to cover for Sophie Raworth. She also regularly deputised on both the "Six O'Clock News" and the "One O'Clock News" during this period. In 2004, Williams covered for Raworth on the "Six O'Clock News" during her maternity leave, co-presenting with George Alagiah, and the following year, reported from Sri Lanka and Thailand on the 2004 Indian Ocean earthquake and from Pakistan on the Kashmir earthquake.