Full list of all 69 Borderlands 2 achievements worth 1,625 gamerscore. It takes around 40-50 hours to unlock all of the achievements in the base game.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 4 DLC packs containing 19 achievements worth 625 Gamerscore.
Killed Donkey Mong
Discovered all named locations
Gunzerked continuously for 90 seconds
Discovered all named locations in Eridium Blight, Arid Nexus, and Sawtooth Cauldron
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 Three Horns, Tundra Express, and Frostburn Canyon
Completed Round 5 of any Circle of Slaughter
Defeated Jack
Completed the mission "Data Mining"
Opened the chest at the bus stop in Fyrestone
Completed the mission "Toil And Trouble"
Completed the mission "Where Angels Fear To Tread"
Completed the mission "The Man Who Would Be Jack"
Gave Claptrap a high five
Completed the mission "The Once and Future Slab"
Completed the mission "Shoot This Guy in the Face"
Completed the mission "Wildlife Preservation"
Reached level 25
Killed a Chubby
Completed the mission "Bright Lights, Flying City"
Completed the mission "Rising Action"
Completed the mission "A Train To Catch"
Tipped Moxxi $10,000
Killed a Constructor without it ever building another bot
Purchased 5 items from the black market
Completed the mission "A Dam Fine Rescue"
Completed 20 side missions
Completed the mission "Hunting The Firehawk"
Redeemed 25 tokens
Killed a flying enemy with a thrown Tediore weapon
Reached level 10
Completed the mission "Plan B"
Got an item from Michael Mamaril
Completed the mission "The Road To Sanctuary"
Completed the mission "Best Minion Ever"
Reached level 5
Unlocked 10 customization items
Completed the mission "My First Gun"
Complete level 1 of all non-level-specific challenges with a single character
Allow a Goliath to level up four times before killing him
Reach level 50
Have Purple-rated gear or better equipped in every slot
Kill 100 enemies with the Sabre turret
Phaselock 100 enemies
I can't even capture it on my camera
Remain in Zero's Deception mode for ten seconds straight
Defeated Terramorphous the Invincible
Revive someone from "Fight for Your Life!" that is on your friends list
Complete all side missions
Complete the mission "X Marks the Spot"
Discover all named locations in Oasis and the surrounding Pirate's Booty zones
Complete all Pirate's Booty side missions
Complete the mission "Long Way To The Top"
Complete all Campaign of Carnage side missions
Collect 10 pictures of Moxxi in Campaign of Carnage
Complete the mission "The Fall of Nakayama"
Complete all Hammerlock's Hunt side missions
Discover all named locations in Hammerlock's Hunt
Slay Mister Boney Pants Guy
Introduce thyself to the White Knight
Complete thy quest by rescuing yonder queen
Feed thy noble queen 3 times during one visit to her quarters
Show thine worst enemy, the abomination known as "The Darkness," who is the nerdiest of them all
Unsheath 5 swords from Immortal Skeletaurs without leaving the area
Win the most challenging round in Murderlin's Temple
Wield the Mysterious Amulet
Demonstrate your skill, or lack thereof, at rolling the magical treasure orb of many sides
Vanquish the Ancient Dragons of Destruction