Applegate, 38, dated 41-year-old Lenoble, a bass player and founding member of Porno for Pyros, for two years before becoming engaged on Valentine’s Day (14Feb10) – and now the couple is preparing to start a family.
A date has yet to be set for the wedding, her rep tells People.com.
The Samantha Who? star, who was pronounced free of breast cancer in August, 2008, has previously credited Lenoble with helping her to recover after undergoing a double mastectomy.
She told People magazine last year (09): “I’m very grateful to Martyn for coming along at a time that he did because he’s been my rock through all of this. He gave me something to really want to live for and something to smile about.”
It will be the second marriage for both stars. Applegate was previously wed to actor Johnathon Schaech but they divorced in 2007.