Mohaimin is a solicitor qualified in England and Wales and joined EIIB in June 2005 from Dubai Islamic Bank, where he was Legal Advisor. Prior to that, from October 2000 to July 2004, he was Legal Advisor in the Legal and Sharia'a Compliance Department of Abu Dhabi Islamic Bank.

Mohaimin started his legal career in private practice in London , where he worked for 4 years after qualification. He was one of the first employees of EIIB and involved in its establishment, including its authorisation by the FSA and listing on the London Stock Exchange in 2006.