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
Completed Round 5 of any Circle of Slaughter
Phaselocked 100 enemies
Revived someone from "Fight for Your Life!" that is on your friends list
Defeated Jack
Completed the mission "Data Mining"
Opened the chest at the bus stop in Fyrestone
Completed the mission "Toil And Trouble"
Killed a flying enemy with a thrown Tediore weapon
Completed the mission "Where Angels Fear To Tread"
Completed the mission "The Man Who Would Be Jack"
Discovered all named locations in Sanctuary, Opportunity, and Lynchwood
Reached level 25
Completed the mission "The Once and Future Slab"
Completed the mission "Shoot This Guy in the Face"
Completed the mission "Wildlife Preservation"
Killed a Chubby
Completed the mission "Bright Lights, Flying City"
Completed the mission "Rising Action"
Killed 100 enemies with the Sabre turret
Completed the mission "A Train To Catch"
Completed the mission "A Dam Fine Rescue"
Killed a Constructor without it ever building another bot
Completed 20 side missions
Redeemed 25 tokens
Tipped Moxxi $10,000
Purchased 5 items from the black market
Completed the mission "Hunting The Firehawk"
Unlocked 10 customization items
Gave Claptrap a high five
Completed the mission "Plan B"
Completed the mission "The Road To Sanctuary"
Reached level 10
Completed the mission "Best Minion Ever"
Completed the mission "My First Gun"
Reached level 5
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
Discover all named locations in Three Horns, Tundra Express, and Frostburn Canyon
Discover all named locations in The Highlands, Thousand Cuts, and Wildlife Exploitation Preserve
Discover all named locations in Eridium Blight, Arid Nexus, and Sawtooth Cauldron
Discover all named locations
Have Purple-rated gear or better equipped in every slot
Gunzerk continuously for 90 seconds
Get an item from Michael Mamaril
I can't even capture it on my camera
Remain in Zero's Deception mode for ten seconds straight
Defeated Terramorphous the Invincible
Complete all side missions
Completed all Pirate's Booty side missions
Completed the mission "X Marks the Spot"
Discover all named locations in Oasis and the surrounding Pirate's Booty zones
Collected 10 pictures of Moxxi in Campaign of Carnage
Completed the mission "Long Way To The Top"
Complete all Campaign of Carnage side missions
Completed the mission "The Fall of Nakayama"
Complete all Hammerlock's Hunt side missions
Discover all named locations in Hammerlock's Hunt
Demonstrated your skill, or lack thereof, at rolling the magical treasure orb of many sides
Completed thy quest by rescuing yonder queen
Unsheathed 5 swords from Immortal Skeletaurs without leaving the area
Introduced thyself to the White Knight
Slew Mister Boney Pants Guy
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
Win the most challenging round in Murderlin's Temple
Wield the Mysterious Amulet
Vanquish the Ancient Dragons of Destruction