"We were more than best friends, we were more than soulmates", Mr Combs tweeted.
"I don't know what I'm going to do without you baby", he continued. Official details about the cause of her death have yet to be announced. And I miss you so much.
On Thursday, first responders were called to Porter's Toluca Lake, California home over a potential cardiac arrest episode. One came from Rihanna, who said Porter was "beautiful inside and out."
Kim and Diddy share three handsome children together and were very much in love for many years (even after they split). Together they have a 20-year-old son and 11-year-old twin daughters.
The rapper and the model, who unexpectedly died on Thursday, started dating in 2004 and were on and off for 13 years.
Diddy has taken to social media to share his thoughts on Kim Porter's passing. She also appeared on TV shows "Law & Order" and "Wicked Wicked Games" and had roles in movies "The Brothers" and "Mama, I Want to Sing".
The two were also great co-parents, and the source made it very clear that Diddy had always cared about Kim. I know Puff is hit right now, he loved her for real ...
According to reports, she had recently been unwell and was prescribed antibiotics. "Kim was a lovely loving soul and we will always be reminded of her grace and legacy in the incredible children she left behind".