Matthew Miazga was born on July 19, 1995, in Clifton, New Jersey, and came through the New York Red Bulls academy before signing a homegrown contract with the club in May 2013. He made his first-team debut later that year as an 18-year-old substitute in a 4–1 win at Houston Dynamo, and over the following two seasons established himself as one of MLS's more reliable centre-backs, earning four MLS Team of the Week selections in 2015 alone.
His performances that year — which included strong showings against high-profile attackers like David Villa and Sebastian Giovinco — helped the Red Bulls claim the 2015 MLS Supporters' Shield and earned him the U.S. Soccer Young Male Player of the Year award. He turned down a designated player offer from the Red Bulls to pursue European football, joining Chelsea on a four-and-a-half-year deal in January 2016 for a reported £3.5 million.
Unable to break into Chelsea's first team consistently, Miazga spent several years on loan across Europe — Vitesse (where he won the 2016–17 KNVB Cup), Nantes, Reading, Anderlecht, and Alavés — developing into a composed, physical centre-back comfortable in multiple leagues. He returned to MLS in 2022 with FC Cincinnati, where he has since become a cornerstone of the defence, winning the 2023 MLS Defender of the Year award and a Supporters' Shield.
At international level, Miazga earned his first senior cap for the United States in November 2015 and has gone on to represent the USMNT in World Cup qualifying and the CONCACAF Gold Cup, which the US won in 2017.