The two teams have quickly agreed terms for the transfer of the 22-year-old, who is already in China to pen a two-year-deal with Aleksandar Stanojevic's side
As revealed on a statement on the A-League club's official website, the two teams have concluded negotiations in just 48 hours, and the centre-back has already flown to China to sign a two-year deal with the newly-promoted side.
Dalian, who are currently sitting in midtable in China's top flight, have recently made it clear they will release Australian Mile Sterjovski to open up a spot for Mullen.
Adelaide's Football Director Michael Petrillo confirmed the move is set to be finalised and that the club will benefit from the fee received for the transfer.
"Dalian Aerbin came to us with a substantial fee for Daniel and he expressed his desire to head to China," Petrillo said.
"It was a decision we did not take lightly because Daniel is an integral part of our squad and while it is always sad to lose a player and a character who has been fantastic both on and off the field, it is a wonderful opportunity for him to further his career.
"Providing his medical is successful, we wish him the best of luck and thank him for the contribution he has made during his time here."
Mullen, who has one cap with the Australia national team, leaves Hindmarsh Stadium after 66 A-League appereances and four goals.
He also represented the club at the 2008 Fifa Club World Cup, ifinding the back of the net in their historic 2-1 win over Oceania champions Waitakere United.