Full list of all 80 Borderlands achievements. It takes around 50-60 hours to unlock all of the achievements in the base game on Windows.
The base game contains 50 achievements, and there are 4 DLC packs containing 30 achievements.
Killed the Vault Boss
Killed Flynt
Emerged victorious from an arena match
Won a duel without taking damage
Killed the Rakk Hive
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Rescued a groupmate from death in a co-op game
Killed 15 enemies with the Berserker's action skill
Killed 15 enemies with the Soldier's action skill
Killed 15 enemies with the Hunter's action skill
Killed Krom
I bet you never thought you'd be here.
Discovered Eridian Promontory
Discovered Crimson Lance Enclave
Discovered Krom's Canyon
Discovered Trash Coast
Completed all missions in the Rust Commons
Earned level 30
Earned level 40
Earned level 50
Earned $1,000,000
Won a duel against another player
Completed 15 missions in co-op
Rescued enough Claptraps to earn 42 inventory slots
Discovered The Scrapyard
Killed an enemy plumber-style
Reached proficiency level 10 with any weapon type
Completed all missions in the Arid Badlands
Completed 5 missions in the Rust Commons
Killed 25 enemies with corrosive weapons
Gamed with fame
Raced around the Ludicrous Speedway in record time
Earned level 20
Equipped a class mod for your character
Killed Sledge
Discovered Headstone Mine
Discovered Sledge's Safe House
Killed 25 enemies with shock weapons
Sold 50 guns to a shop
Mastered the technology of Pandora
Applied an elemental artifact
Killed 25 enemies with explosive weapons
Killed 25 enemies with incendiary weapons
Killed 25 enemies by ramming them with any vehicle
Earned level 10
Killed 5 Rakk in under 10 seconds
Killed an enemy with the Siren's action skill
Discovered Skag Gully
Earned level 5
Completed 5 missions in the Arid Badlands
Completed the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
Reached the end of the larger challenge in the Hell-Burbia coliseum
Reached the end of the larger challenge in The Angelic Ruins coliseum
Reached the end of the larger challenge in The Gully coliseum
Reached the end of each of the 3 larger challenges with one character
Completed the Prove Yourself mission
Killed Crawmerax the Invincible
Paid for a worthless tour of the world's largest bullet
Destroyed a Lancer while in a Racer
Completed all missions in Secret Armory
Built the New Car: Monster
Rescued Athena
Destroyed the Lance Depot
Killed each of the loot midgets
Reached Level 51
Reached Level 61
Completed Tannis' crazy request
Defeated the Interplanetary Ninja Assassin Claptrap
The Commandant is dead-trap
Killed Ned... again and again and again
Knoxx is at rest...finally
Read all 6 claptrap statue placards
Collected 5 3D glasses
Found 25 claptrap oil cans
Collected 15 claptrap bobbleheads
Collected 3 panties, 5 fish in a bag, and 15 pizzas