Stewart, 50, who has held a series of senior posts at public companies, will join the retailer in October.
He will be the right hand man to Bolland, who joined in May from grocer Morrisons and is due to outline his long-term strategy for the group in November.
Marks & Spencer was hit in the recession, after tough competition from discount clothing chains like Primark.
The company is now embarking on a new era for improving its performance, with food sales high on the agenda. Stewart is currently chief financial officer at aircraft leasing company AWAS, but from 2005 to 2008 was group finance director at WH Smith.
Before that he spent seven years at holiday firm Thomas Cook.
Bolland said: “Alan has an impressive track record and will be joining us with extensive experience of retail and other highly competitive industries including travel and banking.”
Stewart replaces Ian Dyson who is now boss at Punch Taverns.