Gangs of London offers a variety of modes of play including Story Mode, Gang Battle, Free Roaming, London Pub Games and a unique Game Sharing mode. In Story Mode, players choose the gang they want to lead and must use strategy and skill to stay one step ahead of the competition. Each mission is separated with narratives that guide players through the background story of criminal masterminds fighting for the right to be called London's number one gangster. Gamers can re-play missions from different gang perspectives, allowing for a variety of routes throughout the game.

Combining some of the best elements of turn-based strategy and card games, Gang Battle mode provides players with an interactive map on which they must use criminal force to attack and defend patches of London. Using a combination of skill, nerve and chance, gamers can take on up to four other gamers on a single PSP system, or compete against up to four AI controlled players.

Free Roaming mode allows players to explore and tackle the streets of London on their own terms as they choose between a variety of characters, vehicles, weapons, time of day, and police levels. Additionally, gamers may activate Tourist Mode, where they will be tasked with exploring and photographing the city's most famous landmarks to unlock game extras. If it's pickup and play gaming that players are looking for, Gangs of London also offers a set of British Pub minigames that include darts, pool and skittles.

Gangs of London also supports a completely original Game Share mode that will generate a new level unique to each PSP, with the content dependent on the serial number of the target system. Once activated, players will find themselves faced with uniquely different mission objectives, environments, characters and weaponry.