Maragh grew up in a racing family. His father, Collin, was a jockey in his native Jamaica and is now a trainer in South Florida, and his brother, Shamir, began his career as a jockey in 2010.
Maragh arrived in the U.S. at the age of 13, though his parents would not let him ride competitively until he graduated from high school. He worked on farms and galloped horses and made his debut with a single race in 2003. Maragh struggled to get good mounts in Florida, but he attracted the attention of retired Hall of Fame jockey Angel Cordero Jr., who brought him to New York in 2004. He was the leading apprentice at the 2004 Meadowlands meet and was the overall runner-up the next two years.
By 2008 Maragh was well established in New York and began riding at Saratoga that summer. He rode stakes-winning fillies Musical Note and Negligee in 2009, when he posted career-bests of 236 victories and $11.7 million in purse earnings. His top horses in 2011 were Grade 1 winners Tizway, Caleb's Posse and Currency Swap. Maragh finished third in the Kentucky Derby aboard Mucho Macho Man in 2011.
Maragh was the regular rider of two-time (2012 and 2013) Breeders' Cup Filly & Mare Sprint winner and Eclipse champion female sprinter Groupie Doll. In 2014 he rode Kentucky Derby hopeful Wicked Strong to victory in the Wood Memorial.