The Birmingham Mail says the American centre-back has been tracked by Alex McLeish for some time and advanced talks have been held on several occasions.
Negotiations with Onyewu’s agent stalled recently but most details have been agreed between both parties.
The defender’s recent club Standard Liege have been resigned for some time to the fact that the free agent is Blues-bound.
An article that appeared on the Belgian club’s official website at the end of last week suggested that Onyewu was set to sign a three-year contract at St Andrew’s.
The piece, dated May 29, read: “As we told you exclusively in yesterday’s tenth edition of Standard, Oguchi Onyewu is on his way to the Premier League with newly-promoted Birmingham City.”
It continued: “More and more, it appears that England and more precisely Birmingham will be his new home in Europe. The manager Alex McLeish, according to details on the other side of the (English) channel, has made him a priority considering his status as a free agent. The two parties are close to a final agreement and a three-year-old contract could be signed this weekend.”