In a general meeting held yesterday (18 December), 99.98% of shareholders voted to acquire the group in a $400m ( £312m) deal on a cash and debt-free basis.
The approved move will now allow WH Smith to accelerate its growth through “broadly doubling” its International Travel business.
Marshall Retail Group operates across airports, resorts and other tourist retail channels throughout the US.
The American retailer currently trades through 170 sites, 59 of which are in airports, with most of its revenue generated through news, gifts and convenience products.
The proposed acquisition was first announced in a statement published in October.
In the statement, WH Smith said that the deal would provide a “rare and compelling opportunity to accelerate its expansion in the large and fast growing US travel retail market”.
Carl Cowling, chief executive of the WH Smith Group, said: “We are delighted to announce today the proposed acquisition of Marshall Retail Group. MRG is a highly successful US travel retailer with a fast growing airport business.
“This acquisition will accelerate the growth of our International Travel business and combined with InMotion, the market leading digital accessories airport retailer that we acquired last year, will significantly enhance our scale and growth opportunities in the US, a large and fast growing travel retail market.”
He added: “This is an exciting value creating opportunity, entirely in line with our strategy.
“I would like to take this opportunity to welcome Michael Wilkins, CEO, and the entire team across the Marshall Retail Group to the WH Smith Group and we look forward to working together to further develop our business across North America.”
Michael C. Wilkins, Marshall Retail Group CEO, said: “This is an incredible milestone for our business and is testament to the outstanding team at MRG.
“We are proud of our success, particularly our recent growth in airports, and I’m especially excited about the potential this unlocks for MRG in the years to come.”
He added: “We very much look forward to working with such an established and successful global business, with strong heritage, as we continue on our journey together to drive both businesses forward.”
Completion of the deal is expected in the first quarter of 2020.