The races are also broadcast free-to-air in Britain on the ITV television network.
Organisers said the championship would be broadcast globally live and in full on the ITV Sport TikTok channel.
"This is a truly ground-breaking move for the BTCC," said BTCC chief executive Alan Gow in a statement.
"I’m incredibly proud that we will be the first major motorsport championship in the world to have its entire race season streamed live on TikTok.
"Most importantly, this agreement will introduce the BTCC to a massive new and completely different demographic - a younger and more diverse audience - which is exactly what we, and in fact all of motorsport, are looking to achieve."
TikTok, owned by China-based ByteDance, claims to reach more than one billion active monthly users worldwide with 45% of them in the 18-34 age bracket and women making up some 57% of all users.
The BTCC season-opener is at Donington Park on April 27th-28th with the championship featuring 30 races across 10 weekends at circuits around Britain.
