[1] Her roles include Natalie Barnes in Coronation Street (1997–2000), Steph Haydock in Waterloo Road (2006–2010 2025), and Trish Minniver in Hollyoaks (2021–2022).

Welch was successful in her application, and graduated in 1979, gaining her Equity card while teaching dance at the Watford Palace Theatre.

[6] Welch gained even wider notability in 1997, when she was cast as Natalie Horrocks in the long-running ITV soap opera Coronation Street.

[10] Originally portrayed as a femme fatale, Natalie rose to respectability by becoming landlady of the soap's famous public house, The Rovers Return.

[11] In 2000, the Coronation Street producers wanted Welch to perform a storyline involving Natalie having a miscarriage, but she refused, saying that the character had already lost her husband and son.

A spokesperson for Granada TV commented, "The character [Natalie] will be gone as she moves to somewhere new, we wish Denise well both for the birth of her baby and for her future career.

She guest-starred twice in ITV's long-running police drama The Bill (in 1997 and 2006), and has also appeared in the BBC's Doctors (2004), Down to Earth (2004–2005) and Born and Bred (2002–2003).

[13][14] Welch originally won the role of Frances Myers in Bad Girls, but ended up declining it owing to illness at the time; her future Waterloo Road co-star Eva Pope received the part instead.

[15][16] Welch left Waterloo Road without intending to return for Series six, but eventually decided to come back for episodes nine and ten.

"[25] Welch made her initial appearance as Alison on 3 May 2016, with fans praising her performance and insisting she was given a permanent role in the soap.

[30] In May 2020, Welch appeared as Doll Belvedere in the online series Dun Breedin, written by and starring Julie Graham alongside Angela Griffin, Alison Newman, Tracy-Ann Oberman and Tamzin Outhwaite in leading roles.

[33] Welch has presented numerous television shows, and also appeared in a series of SCS adverts promoting soft furnishings.

She also participated in Playing the Part, a documentary on BBC One on 21 May 2009, in which she went back to her old secondary school, Consett Community Sports College, and taught there for a week.

In April 2010, Welch appeared with her husband Tim on ITV's All Star Mr & Mrs and donated their runner-up prize of £5,000 to Children North East.

She also appears in the biannual benefit concert Sunday for Sammy, recently parodying the show Loose Women as "Slack Lasses".

On the eighth week of the show, which was broadcast on 6 March 2011, she and Evers were the seventh couple to be voted out of the competition after losing the skate-off to army soldier, Johnson Beharry.

[42] It is believed that Welch "walked out" of Loose Women in October 2013 due to differences with the new director of ITV, Helen Warner.

[45] In early September 2020, Welch appeared on This Morning claiming in her interview with Eamonn Holmes and Ruth Langsford that the media and the authorities are "fear-mongering" over the COVID-19 pandemic.