The youngster will join up with the club's academy after July 1 after a successful trial was converted into a permanent move.
Tauriainen also had trials with Serie A duo Juve and Inter before agreeing to join Chelsea, with him having been pictured holding a Chelsea shirt alongside Frank Lampard on social media.
The midfielder is widely regarded as one of Finland's most highly-rated young players and currently captains his country at Under-16 level.
He is the son of former Finland international Pasi Tauriainen, while his 18-year-old brother, Julius, is currently at Freiburg in their Under-19s team.
Tauriainen's childhood club FC Wild confirmed the details of the contract in the following statement: '"Jimi Tauriainen has signed a three-year deal with Chelsea FC under which he will join the club on July 1, 2020.
"Jimi started his career at FC Wild in 2009 at the age of five, playing for his boyhood club for seven years before moving to HJK in 2016 at the age of 12."
The 16-year-old will join up with a host of Nordic youngsters in the academy at Cobham Training Centre including the likes of Finnish youngster Lucas Bergstrom, Norwegian talent Bryan Fiabema and Edwin Andersson from Sweden.
The announcement came on a busy day for Chelsea, with the Blues having also renewed Ian Maatsen's contract until 2024 with an option for another year.
The Dutchman is one of eight youth team players to make their debut under Lampard this season after a cameo appearance in the Carabao Cup against Grimsby Town.
"I’m properly settled here at Chelsea," Maatsen said upon signing his new contract. "I have good houseparents (who Maatsen lives with in England), good team-mates and friends here. My language is good now – I’m really settled.
"The season for me has been quite good. In the Academy, we were unlucky to not progress in the UEFA Youth League but I was very happy to make my first-team debut. Next season I have to keep pushing and give the same performances.
"We need to make sure we win the FA Youth Cup this year and in the Under-23s league we are unbeaten so we have to make sure we continue the good work."
Chelsea are now focused on agreeing new deals with Tammy Abraham and Tino Anjorin, who made his Premier League debut in the 4-0 win over Everton. The pair have yet to put pen to paper on contract extensions despite talks having taken place for a number of months.