The 22-year-old Belgian striker has completed his £33.2million move to Stamford Bridge from French club Marseille and is looking forward to linking up with a pair of national teammates and a new manager in West London.
"I am delighted to sign for one of the biggest clubs in Europe and embark on the next chapter in my career," he told the club's official website.
"I hope I can help Chelsea win many trophies during my time at Stamford Bridge.
"This is a fantastic opportunity for myself and my family, I am looking forward to playing in the Premier League next season."
Former Standard Liege young gun Batshuayi has spent the past two seasons with Marseille, scoring 33 goals in 78 appearances.