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