Bosses said the deal will allow it to accelerate the growth of WH Smith's international travel business, coming just one year after buying another US travel retailer InMotion for £155m.
It estimated the US airport travel retail sector to be a $3.2 billion market opportunity.
Incoming chief executive Carl Cowling said: "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."
The update to the market came on the same day as the retailer unveiled its full-year results, showing sales rose 11 per cent across the entire WH Smith business to £1.4bn, with travel sales up 22 per cent.
Revenues from its high street dropped 2 per cent to £580m in the year to 31 August.
Group pre-tax profits were up 1 per cent to £135m.
Donald Brown, senior investment manager at Brewin Dolphin, said: “WH Smith continues to be a tale of two businesses. Despite the challenging retail backdrop, the group is delivering strong growth at its travel division, where its 1,019 units delivered a 22 per cent rise in sales.
"This compared to flat sales on the high street, only supported by healthy stationery sales.
"The planned acquisition of the US-based Marshall Retail Group will add 170 new locations, including 59 at airports. This could be a significant move for WH Smith and a declared 8 per cent increase in the final dividend should be viewed as a positive that the balance sheet can cover the extra debt.”