The Blues booked their place in the last four after going past FC Porto in the quarter finals over two legs.
They progressed 2-1 on aggregate, winning the first leg 2-0 and losing the second leg 1-0 against the Portuguese side.
Drogba, who won the competition with Chelsea in 2012, was delighted with the outcome.
He tweeted after the second leg against Porto: "Slowly but surely @ChelseaFC," followed by three blue love heart emojis.
Slowly but surely @ChelseaFChttps://t.co/moxT6hYwGU
— Didier Drogba (@didierdrogba) April 13, 2021