Second from bottom with just two points from their first five games, Copenhagen fired Belgian coach Jacobs, and on Wednesday evening Solbakken was back in the Danish capital to take up his old job.
"The results we as a club have achieved in the last few months are not acceptable for FC Copenhagen, and we have therefore decided to discontinue our involvement with Ariel Jacobs," administrative director Anders Horsholt said in a statement from the club.
Solbakken, a hugely popular figure at the club where he won six titles as a manager, has struggled in management at FC Cologne and Wolverhampton Wanderers since leaving the Danish club two years ago.
"It was both an easy and a difficult decision," the wise-cracking Norwegian told a press conference, before displaying a flash of the humour that made him a favourite in Copenhagen.
"I need to get back out on the training ground again - at least, that's what my wife says."
"We (Copenhagen) won the championship relatively easily last year, and I do not think that the squad as a whole is weakened," added the 45-year-old.
"But we have to realize that the situation has been turned on its head, and that's why we've come to this conclusion."
Solbakken's first match in charge will be at home to FC Vestsjaelland on Sunday.
(Reporting by Philip O'Connor, editing by Nick Mulvenney)
