Parker failed to send out a warning to the division's biggest names such as Anthony Joshua, producing a workmanlike display against his former sparring partner and failing to land any telling blows.
The hulking Cojanu only took the fight at short notice, following the withdrawal of Hughie Fury, and seemingly enjoyed the bout, spending the 12 rounds goading Parker and playing up to the crowd.
But, while he took Parker's punches well, Cojanu never posed a great threat himself and Romania will have to wait for a first heavyweight champion.
