Sky News reported that her appointment was announced internally to staff last month but not otherwise made public.
She left the FCA alongside Clive Adamson in December following the release of a report criticising executives over a blunder that affected insurance companies' share prices.
Dollar Financial - DFC Global's UK arm - includes Payday UK, Payday Express, The Money Shop and Ladder Loans, and is the UK’s second largest payday lender. However it came under fire from the FCA last year and was ordered to refund a total of £700,000 to customers after it approved loans outside its lending criteria.
Yesterday, the FCA released its review of the payday loans industry, concluding that although firms beginning to take a more customer-focused approach, too many firms have been failing to meet the requirements to treat customers in arrears fairly.
The review, which covered 60% of the market, found serious non-compliance and unfair practices in all firms reviewed, leading to poor outcomes for many customers and in some cases, serious detriment and financial loss.
In March 2014, the FCA announced a probe into closed-book policies dating back to the 1970s, causing shares of major insurance companies to drop by up to 22% before the review was clarified.
McMillan was among four FCA executives who lost their bonuses after a report criticised the way the FCA handled market sensitive information, and the length of time the firm took to clarify the review.
She later announced that she would be leaving the organisation as part of 'structural changes'.
On Monday, it was announced that Clive Adamson is set to join Prudential, possibly as a non-executive director.
