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