The 40 million euro (£35.2 million) deal, which includes some of Air Berlin's operations at Tegel airport, leases for up to 25 A320 aircraft and the taking on of about 1,000 of Air Berlin's pilots and cabin crew, will make easyJet the largest carrier in the German capital.
The European Commission said the acquisition would not hurt competition, confirming a Reuters report on Dec. 4.
"EasyJet's plans to buy certain Air Berlin assets will not reduce competition and we have approved it today," EU Competition Commissioner Margrethe Vestager said in a statement.
"Our decision enables easyJet to grow its presence at Berlin airports and start competing on new routes to the benefit of consumers."
EasyJet said it expected to complete the purchase in the near future. Last week it announced a winter schedule for Tegel and will start competing with Lufthansa on German domestic routes from next month.
Booming tourism demand lifted passenger numbers at Berlin's Tegel and Schoenefeld airports by a combined 11.4 percent last year to almost 33 million.
Lufthansa, which wants to purchase Air Berlin units Niki and LGW, will have to give up more airport slots and routes to address competition concerns or face a full-scale EU investigation, a person familiar with the matter told Reuters last week.
Air Berlin on Tuesday said that there were no other bidders for Niki after talks with Thomas Cook failed to result in a new offer, leaving Niki's future uncertain if Lufthansa's bid is rejected on competition grounds.
The Commission, which is scheduled to decide on Lufthansa's case by Dec. 21, will open a full-scale investigation if the airline fails to address its concerns.
($1 = 0.8522 euros)
(Reporting by Foo Yun Chee and Philip Blenkinsop in Brussels; Additional reporting by Alistair Smout in London and Andreas Cremer in Berlin.; Editing by Jane Merriman and David Goodman)
By Foo Yun Chee