Full list of all 75 Borderlands 2 achievements worth 1,875 gamerscore. It takes around 60-80 hours to unlock all of the achievements in the base game.
The base game contains 69 achievements worth 1,625 Gamerscore, and there is 1 DLC pack containing 6 achievements worth 250 Gamerscore.
Completed all Hammerlock's Hunt side missions
Completed all side missions
Defeated Terramorphous the Invincible
Vanquished the Ancient Dragons of Destruction
Completed all Pirate's Booty side missions
Completed the mission "Long Way To The Top"
Wielded the Mysterious Amulet
Completed thy quest by rescuing yonder queen
Demonstrated your skill, or lack thereof, at rolling the magical treasure orb of many sides
Unsheathed 5 swords from Immortal Skeletaurs without leaving the area
Introduced thyself to the White Knight
Discovered all named locations in Hammerlock's Hunt
Completed the mission "The Fall of Nakayama"
Discovered all named locations in Oasis and the surrounding Pirate's Booty zones
Completed the mission "X Marks the Spot"
Defeated Jack
Completed the mission "Data Mining"
Completed the mission "Toil And Trouble"
Completed the mission "Where Angels Fear To Tread"
Completed the mission "The Man Who Would Be Jack"
Had Purple-rated gear or better equipped in every slot
Completed the mission "The Once and Future Slab"
Completed the mission "Shoot This Guy in the Face"
Gunzerked continuously for 90 seconds
Completed the mission "Bright Lights, Flying City"
Completed the mission "A Dam Fine Rescue"
Reached level 25
Reached level 50
Completed the mission "Hunting The Firehawk"
Killed Donkey Mong
Collected 10 pictures of Moxxi in Campaign of Carnage
Completed the mission "The Road To Sanctuary"
Completed the mission "Best Minion Ever"
Killed 100 enemies with the Sabre turret
Completed the mission "Rising Action"
Completed the mission "A Train To Catch"
Phaselocked 100 enemies
Unlocked 10 customization items
Reached level 10
Reached level 5
Completed the mission "Plan B"
Won the most challenging round in Murderlin's Temple
Slew Mister Boney Pants Guy
Completed the mission "Wildlife Preservation"
Got an item from Michael Mamaril
Redeemed 25 tokens
Completed the mission "My First Gun"
Killed a Chubby
Revived someone from "Fight for Your Life!" that is on your friends list
Opened the chest at the bus stop in Fyrestone
I can't even capture it on my camera
Killed a Constructor without it ever building another bot
Allowed a Goliath to level up four times before killing him
Showed thine worst enemy, the abomination known as "The Darkness," who is the nerdiest of them all
Purchased 5 items from the black market
Killed a flying enemy with a thrown Tediore weapon
Completed Round 5 of any Circle of Slaughter
Completed 20 side missions
Completed all Campaign of Carnage side missions
Fed thy noble queen 3 times during one visit to her quarters
Completed level 1 of all non-level-specific challenges with a single character
Remained in Zero's Deception mode for ten seconds straight
Gave Claptrap a high five
Tipped Moxxi $10,000
Discovered all named locations in Three Horns, Tundra Express, and Frostburn Canyon
Discovered all named locations in Sanctuary, Opportunity, and Lynchwood
Discovered all named locations in The Highlands, Thousand Cuts, and Wildlife Exploitation Preserve
Discovered all named locations in Eridium Blight, Arid Nexus, and Sawtooth Cauldron
Discovered all named locations
Equipped effervescent-quality gear in all slots (except class mod).
Allowed Tiny Tina to arm the moonshot cannon.
Defeated Haderax the Invincible.
Completed the mission "Paradise Found".
Defeated the Dark Web.
Activated the Backburner's firewall.