This is a list of all missions in Grand Theft Auto III, sorted by type, island and mission-giver. There are 51 storyline missions, 17 phone missions, 4 Off-road Missions and 4 Remote Controlled Missions.
Claude is betrayed by his girlfriend Catalina when she shoots him during a bank heist, leaving him for dead. He survives and is arrested, but on the way to the penitentiary, the Colombian Cartel ambushes the convoy to kidnap another prisoner, destroying the bridge in the process and isolating the island of Portland from other parts of Liberty City, and he and another prisoner named 8-Ball manage to escape. With his new allie, he eventually forms a connection with the Leone family by destroying the neighboring Triads and Forelli family. He finds out that Catalina has become a co-leader of the Colombian Cartel, and eventually destroys their ship filled with the drug SPANK. However, Salvatore Leone has grown paranoid and no longer trusts easily, so when Maria lies and says that she and Claude are having an affair just to spite him, he sends Claude to his death by planting a bomb in a car he ordered Claude to take away. Maria finds out and warns Claude just in time and, along with Yakuza leader Asuka Kasen, they leave Portland on a boat to Staunton Island.
- Introduction: Cutscenes depicting Catalina's betrayal of Claude, the explosion which leaves Portland isolated from the rest of the city and Claude's escape with 8-Ball.
- Give Me Liberty: Go to Luigi's club with 8-Ball.
- Luigi's Girls: Bring Misty to Luigi's club.
- Don't Spank Ma Bitch Up: Kill a drug dealer and steal his car.
- Drive Misty For Me: Drive Misty to Joey's garage.
- Pump-Action Pimp: Kill two pimps.
- The Fuzz Ball: Bring as many prostitutes as possible to the Old School Hall.
- Mike Lips Last Lunch: Arm Mike Forelli's car with a bomb and blow him up.
- Farewell 'Chunky' Lee Chong: Kill Lee Chong.
- Van Heist: Steal a Securicar and bring it to a garage in Portland Harbor.
- Cipriani's Chauffeur: Drive Toni Cipriani to the Laundry and to his home.
- Dead Skunk in the Trunk: Bring a car to the car crusher.
- The Getaway: Drive three mafia members for a bank job.
- Taking Out The Laundry: Destroy three Laundry cars.
- The Pick-Up: Pick up a briefcase and take it to the Cipriani Restaurant.
- Salvatore's Called A Meeting: Bring Joey, Luigi and Toni to Salvatore Leone's mansion.
- Triads and Tribulations: Kill three triad warlords.
- Blow Fish: Blow up the Triad's fish factory.
- Chaperone: Drive Maria to Chico and a party in Atlantic Quays.
- Cutting The Grass: Follow and kill Curly Bob.
- Bomb Da Base: Act I: Go and talk to 8-Ball to purchase the Sniper Rifle.
- Bomb Da Base: Act II: Help 8-Ball to blow up the Cartel Ship.
Claude is now a rogue from the gangs in Portland, with the Leone Family and the Triads after him, and begins making a new connection in the Yakuza. He assassinates Salvatore to prove he is no longer working for him, and he is introduced to Asuka's powerful brother Kenji and a corrupt policeman named Ray who helps him in exchange for doing his dirty work. Ray introduces him to Donald Love, a billionaire real estate mogul, who Claude helps as well for the benefit of Love and his company. However, to start a gang war and lower the real estate price of land Love wants, he steals a Colombian Cartel vehicle and kills Kenji, igniting a war between the two. He eventually finds Catalina again, who kidnaps Maria, kills Miguel and Asuka, and ransoms Maria for $500,000.
- Sayonara Salvatore: Kill Salvatore Leone.
- Under Surveillance: Kill the mafia spies on Staunton Island.
- Paparazzi Purge: Kill a paparazzi.
- Payday For Ray: Bring Ray's money to him.
- Two-Faced Tanner: Kill Tanner.
- Kanbu Bust-out: Break a high ranked Yakuza member out of jail.
- Grand Theft Auto: Bring three sport cars to a garage in six minutes.
- Deal Steal: Ambush a deal between the Cartel and the Yardies.
- Shima: Collect the briefcases of protection money.
- Smack Down: Kill as many yardie dealers as possible.
- Silence The Sneak: Kill Leon McAffrey.
- Arms Shortage: Defend Phil Cassidy from the Colombian Cartel.
- Evidence Dash: Pick up six images and torch the car that the pictures are in.
- Gone Fishing: Kill Ray's partner.
- Plaster Blaster: Kill Leon McAffrey, who is still alive.
- Marked Man: Take Ray to the airport and then go to his lock-up.
- Liberator: Rescue an oriental gentleman from the colombians.
- Waka-Gashira Wipeout: Kill Kenji Kasen in a Colombian car. Note: that by completing this mission, Kenji will be dead thus any mission from Kenji that has not yet been completed will be cancelled, and 100% completion will not be completed.
- A Drop In The Ocean: Pick up six packages thrown in the ocean from a plane. Unlock Shoreside Vale
- Grand Theft Aero: Find the real packages and bring them to Donald Love.
- Escort Service: Defend a Securicar in it's way from the Colombian Cartel.
- Decoy: Get inside a Securicar and act as a decoy around for three minutes.
- Love's Disappearance: You can't find Donald Love so you decide to leave the Love Media building.
- Bait: Lead three Colombian death squads into a trap.
- Espresso-2-Go!: Destroy nine espresso stands.
- S.A.M.: Blow up a Dodo with a rocket launcher and bring the SPANK packages to Asuka.
- Ransom: Asuka and Miguel are killed, Maria is kidnapped by Catalina, and you find a letter left by her.
- Turismo: Win a street race.
- I Scream, You Scream: Arm an ice cream truck with a bomb and blow up a group of gang members.
- Trial By Fire: Burn twenty-five Triads in two minutes.
- Big 'N Veiny: Pick up some magazines and take them to XXXMags in Red Light District
- The Crook: Bring a bank manager to the dog food factory and crush the evidence.
- The Thieves: Bring two thieves to the food factory and respray Marty's car.
- The Wife: Bring Marty's wife to the food factory and and dump the car into the sea.
- Her Lover: Bring Carl to the food factory.
- Bling-Bling Scramble: Win a checkpoint race.
- Uzi Rider: Kill ten Diablo gang members.
- Gangcar Round-Up: Bring three gang cars to a garage in Newport.
- Kingdom Come: Destroy some SPANKed up madmen vans and reveal the betrayal of King Courtney.
- Uzi Money: Drive-by 25 Purple Nines in two minutes.
- Toyminator: Destroy three gang cars with an RC Bandit.
- Rigged to Blow: Bring an armed car to a garage before it explodes.
- Bullion Run: Pick up as many pieces of bullion as possible and take them to a garage.
- Rumble: Kill as many Purple Nines as possible using only melee weapons.
- Patriot Playground: Pass through fifteen checkpoints at the Portland Beach.
- A Ride in the Park: Pass through twelve checkpoints in the park.
- Multistorey Mayhem: Pass through fifteen checkpoints in the multistorey car park.
- Gripped!: Pass through twenty checkpoints in Cedar Grove.
Remote controlled vehicle missions
- Diablo Destruction: Destroy as many Diablo Stallions as possible with an RC car.
- Mafia Massacre: Destroy as many Mafia Sentinels as possible with an RC car.
- Casino Calamity: Destroy as many Yakuza Stingers as possible with an RC car.
- Rumpo Rampage: Destroy as many Hoods Rumpo XLs as possible with an RC car.