It is possible to achieve 100% completion with the use of cheats.
Portland story missions
- The Introduction
- Mike Lips Last Lunch
- Farewell 'Chunky' Lee Chong
- Van Heist
- Cipriani's Chauffeur
- Dead Skunk in the Trunk
- The Getaway
Staunton Island story missions
- Waka-Gashira Wipeout![note 1]
- A Drop in the Ocean
- Grand Theft Aero[note 1]
- Escort Service
- Love's Disappearance
Shoreside Vale story mission
Remote controlled vehicle missions
- Paramedic (reach and complete Level 12 in one go)[note 2]
- Firefighter (extinguish 60 fires, 20 on each island)[note 2]
- Vigilante (kill 60 criminals, 20 on each island)[note 2]
- Taxi Driver (complete 100 fares)[note 2]
- Emergency Vehicle Import/Export Crane
- Industrial Import/Export Garage List (Portland)
- Suburban Import/Export Garage List (Shoreside Vale)
Unlike most Grand Theft Auto games, there are no rewards for completing the game 100%.
- ↑ 1.0 1.1 1.2 Several missions that contribute to 100% completion can be permanently disabled if other missions are completed beforehand:
- Luigi's missions "Pump-Action Pimp" and "The Fuzz Ball" must be completed before Salvatore's "Last Requests".
- Joey's missions "Dead Skunk in the Trunk" and "The Getaway" must be completed before Salvatore's "Last Requests".
- Kenji's missions "Kanbu Bust-out", "Grand Theft Auto", "Deal Steal", "Shima" and "Smack Down" must be completed before Donald Love's "Waka-Gashira Wipeout!"
- Asuka's mission "Two-Faced Tanner" must be completed before Donald Love's mission "Grand Theft Aero".
- ↑ 2.0 2.1 2.2 2.3 2.4 As the player progresses through the storyline, multiple gangs will become hostile to Claude or have their weaponry upgraded, making vehicle missions and Rampages extremely difficult. It is heavily advised to complete:
- All Portland vehicle missions and Rampages before both "Sayonara Salvatore" (after which the Mafia becomes hostile and begin carrying Pump Shotguns) and "Uzi Rider" (where the Diablos become hostile), preferably before "The Pick-Up" and "Trial By Fire" (where the Triads become hostile).
- All Staunton Island vehicle missions and Rampages before "Kingdom Come" (where the Yardies become hostile)
- All Shoreside Vale vehicle missions and Rampages before the final mission "The Exchange" (where the Colombian Cartel replace Pistols with Uzis and AK-47s.