There are a total of 79 achievements that can be unlocked in Halo 3. 49 were shipped with the game, worth a total of 1000 Gamerscore 
, with another 30 downloadable content achievements worth 750 .[1] Some achievements unlock certain armor permutations.
Note: Following the shutdown of Xbox 360 Halo online services on January 13, 2022, achievements which could only be unlocked through online play are no longer attainable.[2][3]
Campaign[edit]
| Icon
|
Name
|
Description
|
Gamerscore
|
| Level Completion
|
|
Landfall
|
Finish the first mission of the Campaign on Normal, Heroic, or Legendary.
|
20
|
|
Holdout
|
Finish the second mission of the Campaign on Normal, Heroic, or Legendary.
|
20
|
|
The Road
|
Finish the third mission of the Campaign on Normal, Heroic, or Legendary.
|
20
|
|
Assault
|
Finish the fourth mission of the Campaign on Normal, Heroic, or Legendary.
|
30
|
|
Cleansing
|
Finish the fifth mission of the Campaign on Normal, Heroic, or Legendary.
|
30
|
|
Refuge
|
Finish the sixth mission of the Campaign on Normal, Heroic, or Legendary.
|
30
|
|
Last Stand
|
Finish the seventh mission of the Campaign on Normal, Heroic, or Legendary.
|
40
|
|
The Key
|
Finish the eighth mission of the Campaign on Normal, Heroic, or Legendary.
|
40
|
|
Return
|
Finish the final mission of the Campaign on Normal, Heroic, or Legendary.
|
50
|
| Campaign Completion
|
|
Campaign Complete: Normal
|
Finish the Campaign on Normal.
|
125
|
|
Campaign Complete: Heroic
|
Finish the Campaign on Heroic
(unlocks achievement for Normal, if not earned).
|
125
|
|
Campaign Complete: Legendary
|
Finish the Campaign on Legendary
(unlocks achievement for Normal and Heroic, if not earned).
|
125
|
| Skulls
|
|
