The 33-year-old reality star - who shares two-year-old son Mason, and a four-month-old daughter Penelope with her boyfriend of almost six years - is said to be over the moon after Scott popped the question during their trip to Paris, France last week.
Scott's aunt Laurie Disick confirmed the news to Star magazine: ''We're all so thrilled they've finally decided to get engaged. We're all so fond of Kourtney, and we wish them a long, happy marriage.''
The romantic proposal was reportedly filmed for their finale of the reality TV star's upcoming news series 'Kourtney and Kim Take Miami', which hits screens in January.
An insider also revealed: ''Scott's actually been planning to propose for a while. But He just wasn't sure when the moment would be right.''
The 29-year-old restaurant owner was spotted in Fort Lauderdale, Florida with a male friend checking out engagement bands at Levinson Jewelers late last month.
An onlooker said: ''Scott was most definitely shopping for engagement rings, and all of them were large!
''Scott and his friend looked at a whole selection of amazing rings, all diamond, all different cuts, sizes, settings -- he certainly is taking his time and wants to make the right purchase.''
Earlier this month, Kourtney was reportedly angry with her mother Kris Jenner for trying to persuade Scott to propose so they could film the wedding for a one-hour special episode, similar to her sister Kim's televised nuptials with estranged husband Kris Humphries last year.
But she now appears to be thrilled and mysteriously tweeted some of the lyrics of Rihanna's song 'Diamond' yesterday (19.11.12), writing: ''Shine Bright Like A Diamond.''