The move officially went through on Wednesday after weeks of negotiations between Gladbach and the Dutch club, and after the 21-year-old successfully passed a medical before signing on the dotted line.
The Holland international was Gladbach’s number one transfer target this summer and they beat off competition from numerous other European clubs to sign one of the Dutch Eredivisie’s most prolific scorers.
De Jong found the back of the net 39 times in 75 appearances over the past two seasons for Twente.
"We are really delighted that this transfer has finally gone through," said Gladbach’s director of sport Max Eberl.
"Luuk will be able to travel with us into our training camp at Tegernsee on Friday."
De Jong joins a club who are embarking on their first ever season in the Champions League and his experience with Twente in that competition and the Europa League last season were important factors in his arrival.
"With Luuk de Jong, we are getting a highly-talented attacker who, despite being only 21, already has a wealth of experience in Europe with FC Twente and the Dutch national team," added Eberl.