The 2018 NBA Finals was the championship series of the National Basketball Association's (NBA) 2017–18 season and conclusion of the season's playoffs. In this best-of-seven playoff, the defending NBA champion and Western Conference champion Golden State Warriors swept the Eastern Conference champion Cleveland Cavaliers in four games to repeat as champions for the first time in franchise history, having previously won in 2017. The series began on May 31, and ended on June 8 with the first NBA Finals sweep since 2007. Golden State Warriors small forward Kevin Durant was named the NBA Finals Most Valuable Player (MVP) for the second consecutive year, after averaging 28.8 points, 10.8 rebounds, and 7.5 assists in the series. Durant became the first and only player in the history of the Warriors franchise to win two consecutive NBA Finals MVP Awards and also the first and only player in the history of the NBA to have been named two NBA Finals MVP in the first two seasons with a team.

The Finals was the first time in any of North America's four major professional sports leagues that the same two teams met for the championship for four consecutive years. Entering the series, the Warriors, who had home-court advantage over the Cavaliers, were noted by various sports media outlets as one of the biggest NBA Finals favorites in recent history.

In a tightly-contested Game 1, George Hill missed one of his two free throw attempts at the end of the game, and J. R. Smith got the rebound, thinking the Cavaliers were leading, but the game was tied at the end of regulation. The Warriors dominated in overtime and went on to win the next three games to complete the sweep. The series broke the record set by the 2014 NBA Finals for highest average scoring differential per game (15.0) for an NBA Finals series. As of 2025, the 2018 Finals are the most recent NBA Finals to have a repeat champion and the most recent where the losing team was swept.

This was the Golden State Warriors' fourth consecutive trip to the NBA Finals. During the 2017–18 offseason, the Warriors re-signed their core players, including reigning NBA Finals MVP Kevin Durant to a two-year, $53 million contract and point guard Stephen Curry to a five-year contract worth $201 million. Golden State also re-signed Andre Iguodala, Shaun Livingston, Zaza Pachulia, and David West. A free agent acquired during the offseason was guard Nick Young.

The Warriors finished the 2017–18 regular season with a 58–24 record, winning the Pacific Division and securing the 2nd seed in the Western Conference. In the playoffs, Golden State defeated the San Antonio Spurs in five games in the first round, eliminated the New Orleans Pelicans in five games in the Western Conference Semifinals, and despite major obstacles, they defeated the top-seeded Houston Rockets in seven games in the Western Conference Finals.

The Warriors entered the series as heavy favorites, aiming to repeat back-to-back titles after losing their quest in 2016.

This was the Cleveland Cavaliers' fourth consecutive trip to the NBA Finals, and fifth appearance overall. This was also the eighth consecutive NBA Finals appearance for Cavaliers small forward LeBron James, a streak that began in 2011 when he was with the Miami Heat.

Prior to the 2017–18 season, All-Star point guard Kyrie Irving requested to be traded away from the Cavaliers. Although James was against the idea of trading him away, the Cavaliers agreed to Irving's request, trading him to the Boston Celtics in exchange for point guard Isaiah Thomas, small forward Jae Crowder, center Ante Žižić, the first-round pick from the Brooklyn Nets in the 2018 NBA draft and the Miami Heat's 2020 second round pick. Miami's second round pick was added as compensation after Isaiah Thomas failed his physical. Other major changes included shooting guard Dwyane Wade signing with the Cavaliers, thus reuniting with James from their time together on the Big Three-era Miami Heat, and the signing of point guard Derrick Rose to a one-year contract.