Crime Boss is focused around missions undertaken by teams of four criminals. The player controls one of the criminals and cooperates with either other players or AI-controlled teammates to pull off heists in a first-person perspective. The gameplay has frequently been compared to the Payday series of games. The players need to collect enough loot from the target (banks, trucks, jewelry stores, etc.), but the longer they take, the greater the likelihood of police reinforcements arriving.

There are several ways that the missions are set up. The simplest option is as quick play one-ofs. There are also six mini-campaigns of three missions chained in a row with a loose connecting story for each called "Urban Legends". There is a single-player campaign with roguelike elements where the player attempts to expand their territory across Rockay City after the previous leader of the underground dies. The player allocates gang members to fight turf wars, buys new weapons, and goes on missions to attempt to take new territory—but if the player character dies in a mission, their quest to become Crime Boss is over. In the same way, hired crew members who die or are arrested on missions are also lost forever.

The feel of the game is consciously imitative of 1990s crime movies such as Heat. Rockay City itself is set in a Florida reminiscent of Miami Vice.