Takayo Nembhard had travelled up from his home in Bristol to attend the carnival in West London, but was sadly stabbed to death during the event.
Oshian Edwards is due to give birth in November, and shared her devastating loss on Instagram.
She wrote: “Takayo my sweet beautiful boy.
“All I can ask is why over and over again.
“You were the most kind-hearted, loving, funny and caring person.
“I’m sat here with sore eyes and a heavy heart as I’ve cried consistently for the last 12 hours while carrying your unborn son.
“I will remind him daily about how great you were as a son, brother, boyfriend and friend too!"
She continued: "The love I have for you will never stop and I will honour your name everyday.
“I will look after your sisters to the best of my ability. They loved you so much. We all did.
“I held your hand yesterday for the last time as you lay there lifeless and baby T kicked me straight away and it broke me.
“It’s just not fair. We live in such a cruel world. I’m so angry yet keep being told I have to stay strong for the baby.
“The support you had at the hospital yesterday from family and friends was so lovely. I only wish you knew how loved you really were.
“I love you wholeheartedly and I’m so glad I get to share something so special with you and I know I’ll see you in him everyday.”
After Nembhard was stabbed on Monday, ambulance services were rushed to the Ladbroke Grove area, before he was rushed to hospital where he later died.
Announcing the sad news on the musician’s Instagram page, his manager Chris Patrick said: "2 years ago a young 19 year old man came from Bristol to meet me at my studio with his dad, his name was Takayo Nembhard AKA TKorStretch.
“That meeting took us on a journey…we recorded some great music together. His talent was endless and I can tell you guy he was close to greatness!
"So it's with a heavy heart that I bring the news that Takayo (TKorStretch) passed away last night.
"He came from Bristol to simply have a good time at the London carnival and this is the end result!
"My deepest condolences to TK's mother and father, his brother and two sisters, girlfriend and child that will never meet his father!
"TK was a good kid, a good guy and what has happened breaks my heart... Rest in peace my friend. Xxxx"
London’s Mayor Sadiq Khan has since condemned the killing, appealing for anyone with information to come forward.
He tweeted: "I am sickened by this awful attack. Violence has no place on our streets and we are doing everything in our power to root it out.
"I urge anyone with information to contact the police on 101 or anonymously by @CrimeStoppersUK. There is no honour in staying silent."
Dr Alison Heydari, Commander of Local Policing for the Metropolitan Police, said: “Regrettably, on Monday evening we saw a number of violent incidents and a 21-year-old man has lost his life.
“Our thoughts are with his family as they come to terms with their terrible loss.
“A murder investigation is under way, led by homicide detectives from the Met’s Specialist Crime Command. They will pursue every possible line of enquiry to identify those responsible and bring them to justice."
On Monday, the Met said that there had been 76 arrests made at the carnival for ‘a variety of different offences’.
Featured Image Credit: @tkorstretch / @oshianedwards_ / Instagram