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July 26, 2026Sources cited
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Entertainment • YouTuber

KSI

KSI is a British influencer, musician, and former professional boxer best known for his YouTube career, Sidemen membership, and crossover boxing matches.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

KSI, born Olajide Olayinka Williams Olatunji on 19 June 1993 in London, England, is a British influencer, musician, and former professional boxer. He is best known for his YouTube career, membership in the Sidemen, and crossover boxing matches. KSI has also been involved in business ventures including Prime Hydration and Misfits Boxing, and has a global reach that includes Canadian audiences.

Early life and identity

KSI was born Olajide Olayinka Williams Olatunji in London, England, on 19 June 1993. He is also known by the nickname JJ.

Career

He first gained prominence on YouTube before becoming active in music and crossover boxing. Sources also describe him as a co-founder of the Sidemen and Misfits Boxing.

Business ventures

KSI has co-owned or co-founded brands and companies including Prime Hydration and Lunchly. Some sources also list additional ventures such as Sidemen-related businesses.

Boxing record and public profile

KSI has competed in high-profile boxing matches and is described in sources as a former professional boxer. He remains a major UK internet personality and entertainment figure.

Key facts

  • KSI is the professional name of Olajide Olayinka Williams Olatunji.
  • He became widely known through YouTube and later expanded into music and boxing.
  • He co-founded Misfits Boxing and is associated with several business ventures.
  • He has served as a judge on Britain's Got Talent since 2025.
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Canadian context

KSI is relevant to Canadian readers as a major English-language internet celebrity with global reach in YouTube, music, boxing, and brand partnerships, all of which have audiences in Canada.

Frequently asked questions

Who is KSI?
KSI is the stage name of British influencer, musician, and former professional boxer Olajide Olayinka Williams Olatunji.
How old is KSI?
He was born on 19 June 1993, so he is 33 years old as of 2026.
What is KSI's real name?
KSI's real name is Olajide Olayinka Williams Olatunji.
What happened to KSI?
Available sources describe him as active in entertainment, boxing, and business; one source notes he announced in June 2026 that he was leaving the Sidemen.
How much does KSI weigh?
The sources provided do not give a specific weight figure; one source lists his boxing division as cruiserweight.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/KSI
    Supports: Birth name, birth date, nationality, occupations, Sidemen, Misfits Boxing, business ventures, and Britain's Got Talent role.
  2. USA Today — https://www.usatoday.com/story/sports/boxing/2023/10/10/ksi-everything-to-know-about-youtuber-boxer-entrepreneur/71131099007/
    Supports: Public identity, YouTube fame, boxer-musician-entrepreneur profile, and background.
  3. Simple English Wikipedia — https://simple.wikipedia.org/wiki/KSI
    Supports: Birth name, birth date, career summary, and boxing activity.
  4. Rayo — https://www.hellorayo.co.uk/mfr/entertainment/music/ksi
    Supports: Age, Sidemen departure claim in June 2026, and general career overview.
  5. Famous Birthdays — https://www.famousbirthdays.com/people/olajide-olatunji.html
    Supports: Birth date and age.
  6. Fandom — https://sidemen.fandom.com/wiki/KSI
    Supports: Sidemen association and professional name history.