Kris Jenner wrote Kim Kardashian West a 20-page letter for her 40th birthday.

Kris Jenner

Kris Jenner

The 'Keeping Up With The Kardashians' star spent "a couple [of] hours" penning the lengthy note, and she enjoyed writing the "really beautiful" message for her daughter's big day in October.

She told the 'At Home with Linda & Drew Scott' podcast: "I always thought I would write my kids a letter, but you know, it's really very time-consuming, because I write really long letters.

"So, when it was Kim's birthday, I sat down this past year and wrote her a really beautiful letter about how I felt about her.

"And I think it was like 20 pages long or something like that."

The 65-year-old 'momager' revealed she has already written letters for Kourtney Kardashian, and Kendall and Kylie Jenner, while she's planning touching notes for Rob and Khloe next.

She added: "I'm almost done with the six letters... But I just kind of started with their births, and said this was one of the six greatest days of my life, and kind of the place they hold in my heart. "And then, I got into the different things in life that have meant so much to me and the special moments that I'll never forget. So that, to me, means everything."

Kris urged everyone to write letters to their loved ones and let them know how much they mean to you.

She said: "If I would give anybody any advice, it would be to write a letter to a child or a parent or somebody who's really meant so much in your life, that you just need to get that said, so that they have that."

Meanwhile, she and her famous family are preparing to say goodbye to 'Keeping Up With the Kardashians' after 20 seasons across 14 years, and they all enjoyed getting together to work on it.

She recently said: "It was some of the best quality family time.

"We are always going in so many different directions, and we all have 20 jobs.

"But this really gave us a chance to settle and appreciate the time we were spending together, knowing it was our last season."