[11] She wrote the television drama serials Band of Gold (1995), Playing the Field (1998),[12] Fat Friends (2000), Between the Sheets (2003), and Strictly Confidential (2006).
[13][14] Commenting on the casting for Fat Friends, Mellor said she had wanted genuinely large people to play the parts, calling Ruth Jones and James Corden "the real McCoy".
Mellor had seen Corden in a Tango advert and asked her casting director Beverley Keogh to find him for her because she thought he was perfect for the part.
[5] In a parallel career as a television actress, Mellor appeared in her own adaptation of Jane Eyre (1997), and in other series and films such as the comedy drama Stan the Man (2002), A Good Thief (2002) and Gifted (2003).
[15][16][17] On stage, Kay acted in Three Girls in Blue and she wrote and starred in the one-woman show Queen at the West Yorkshire Playhouse.
She wrote and directed the two-part drama A Passionate Woman which was based on her 1992 stage play and was broadcast on BBC One in April 2010.
Mellor's drama series Love, Lies and Records ran on BBC One in November and December 2017, starring Rebecca Front and Ashley Jensen.
[22] Her ITV drama series Girlfriends, starring Zoë Wanamaker, Miranda Richardson and Phyllis Logan, premiered in January 2018.
[23] The fourth series of The Syndicate aired in March 2021 with a cast including Neil Morrissey, Katherine Rose Morley, Kieran Urquhart, Taj Atwal, Liberty Hobbs, Emily Head, Gaynor Faye, Kym Marsh, Katie McGlynn, Mark Benton, Lorraine Bruce, and Joe Sugg.