- Complete the main story missions ("The Cousins Bellic" to "Out of Commission" (Revenge) or "A Revenger's Tragedy" (Deal)).
- Complete all 10 drug deliveries for Little Jacob.
- Win all 9 races for Brucie Kibbutz at least once.
- Complete all 10 Exotic Exports for Brucie.
- Complete all 9 missions of The Fixer's Assassinations.
- Complete all 30 car thefts for Stevie.
- Brucie Kibbutz - Unlock special ability.
- Little Jacob - Unlock special ability.
- Patrick McReary - Unlock special ability.
- Brucie Kibbutz - Do each available activity once.
- Little Jacob - Do each available activity once.
- Patrick McReary - Do each available activity once.
- Beat a computer or friend at Pool.
- Beat a computer or friend at Darts.
- Beat a computer or friend in a full game of Bowling.
- Beat the high score in the QUB3D arcade game.
- Do all 16 random character missions (excluding Jeff Harlingford, Ivan Bytchkov, Clarence Little, and Cherise Glover).
- Complete all the Most Wanted missions via police computer.
- Do 20 vigilante missions via police computer using the "Recent Crimes" option.
- Kill all 200 Pigeons.
- Complete all 50 stunt jumps.
The reward for 100% completion in GTA IV is a "100% Game Completion." message in the top left corner and the ability to buy an unlimited amount of ammunition, although it still costs the same as before, and the Key To The City Achievement is unlocked. This reward has a bug that is present when the player loads a 100% saved game, which causes all the ammo that was over the original limit to be lost.
Tasks not required
- Complete all of the Roman's Taxi Driver missions (Available from Jamaican Heat to Roman's Sorrow).
- Reach 100% fondness with all five girlfriends.
- Do each available activity once with all five girlfriends each.
- Unlock all three online girlfriends' special abilities.
- Roman Bellic - Unlock special ability.
- Dwayne Forge - Unlock special ability.
- Roman Bellic - Do each available activity once.
- Dwayne Forge - Do each available activity once.
- Mark all locations which you can enter on your map
- Buy all Telephone stuff from Vipluxuryringtones.com (MP3, SFX and Themes).
- Add ZiT! as a phone contact.
- Purchase all clothing.
- Collect the "Happiness Is...Land" Sweater.
- Visit all websites.
- Purchase all weapons.
- Use a Car Wash.
- Watch all television programs.
- Collect all GTA IV Achievement/Trophies.
- For a short while after the release of Grand Theft Auto IV, players could be given a "Key to Liberty City". Only 500 were made.