Marriott was born at Marriott Settlement near Ogden, Utah, and was raised on his father's farm. His father gave him considerable responsibility at an early age: he was sent to San Francisco on his own with 3,000 sheep in railcars at the age of 13.
At the age of 19 and as a devout Mormon, he undertook the traditional missionary work of the church for two years, being assigned to New England. On his way home after completing his mission, he passed through Washington D.C. during the sweltering summer months of 1921. While there:
"He walked from Capitol Hill to the Washington Monument, toiled up the steps to the top, walked back down again, and strolled over to the Lincoln Memorial. Everywhere he went tourists and pedestrians sweltered and sweated in the sultry, humid air. On the way back to his hotel, he just stood there in the street watching the crowds, he couldn't get over it: a push cart peddler would come along the street selling lemonade and soda pop and ice cream, and in minutes he would be cleaned out and on his way to stock up with another cartload"
Marriott graduated from Weber State University, where he served as student body president, with an associate's degree in June 1923 and from the University of Utah with a bachelor's degree in June 1926. Marriott affiliated with the Phi Delta Theta social fraternity at the University of Utah and the Alpha Kappa Psi professional fraternity. After Marriott earned his bachelor's degree, the president of Weber, Aaron Tracy, who had assisted Marriott to enroll there by helping him make up secondary education credits missed due to the Marriott family's ranching efforts, employed him at the school in Ogden. Marriott soon felt the urge, however, to be his own boss. He heard about a cousin's A&W Root Beer franchise and, remembering his experience seeing so many people suffer through the brutal summer heat of Washington, D.C., he decided to look into a venture there.