The Celebrity Big Brother winner said that she is "absolutely thrilled" after boyfriend Lincoln Townley proposed while they were on holiday in Nice.
"I had no idea the proposal was coming," Welch told The Mirror.
The couple met last year and began officially dating after the Loose Women star split from Tim Healy.
She and Healy have started divorce proceedings as Welch plans to marry Townley, who now works as her publicist, next July.
"Lincoln knew fairly early on that Denise was 'the one' and, over the past few months, they have become inseparable. This past year has been incredibly hard but Lincoln has been an absolute tower of strength," a source said.
"He planned the proposal with military precision and even asked for Denise's dad's blessing. It was completely unexpected and Denise was stunned but now she can't wait to plan an amazing wedding."
The couple went shopping for rings on London's Bond Street yesterday. Her children Matthew, 22, and Louis, 11, and Townley's 20-year-old son Lewis will be central to the big day.
Welch, who moved in with Townley earlier this year, is expected to invite Healy and his new girlfriend Joan Anderton to the wedding.