Born on 8 March 2004 in Helsinki, Finland, Jimi Weikko Tauriainen grew up in a football family — his father Pasi is a former Finnish international, and his brother Julius plays professionally in Finland. He started out at FC Wild, a club his father helped found, before joining HJK's academy in 2016. After successful trials with Juventus, Inter Milan, and Chelsea, he made the move to west London in July 2020 at the age of 16, originally as a forward before being developed into a midfielder at Chelsea.
Tauriainen signed his first professional contract with Chelsea on his 17th birthday in March 2021, extending it just four months later. His early breakthrough came on 25 February 2024, when he was included in Chelsea's squad for the EFL Cup Final against Liverpool — a match the club finished as runners-up. Three days later, he made his senior debut as a late substitute against Leeds United in the FA Cup fifth round. He then made his Premier League debut on 2 May 2024, coming off the bench in a 2–0 home win over Tottenham Hotspur.
A versatile, technically composed midfielder, Tauriainen has shown an ability to contribute in tight spaces at the top level. Chelsea continue to view him as a developing asset within their squad, giving him carefully managed opportunities at first-team level. At international level, he has represented Finland across youth groups from under-15 to under-21, though he is yet to earn a senior cap.