The following list contains the storyline missions along with other side missions in GTA III for the 100% completion in the game. Storyline and pay phone missions are listed chronologically on each island they are given at. There are 50 storyline missions along 17 pay phone missions.
- 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 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.
- 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 himself.
- 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: Leon McAffrey is still alive, and you have to kill him.
- 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.
- A Drop In The Ocean: Pick up six packages thrown in the ocean from a plane.
- 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 two 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 Diablos.
- Gangcar Round-Up: Bring three gang cars to a garage in Newport.
- Kingdom Come: Destroy some SPANKed up madmen vans.
- 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 bullion as possible and take it to a garage.
- Rumble: Kill some Purple Nines using 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 missionsEdit
- 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.