Mariano was born in the city of Lihue on the island of Kauai in Hawaii. At the age of four Mariano relocated with her family to California, where she was raised in the city of Mission Viejo with her two older brothers. At the age of 15 she was discovered in Santa Monica, California by a model scout. After graduating from Trabuco Hills High School, she moved to New York City, where she continued to model and attended Pace University as a full-time student, receiving her degree in Speech Communications with a Media Studies Concentration.