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 Pirate's Booty side missions
Discovered all named locations in Oasis and the surrounding Pirate's Booty zones
Completed all Campaign of Carnage side missions
Completed all Hammerlock's Hunt side missions
Discovered all named locations in Hammerlock's Hunt
Completed the mission "The Fall of Nakayama"
Completed Round 5 of any Circle of Slaughter
Won the most challenging round in Murderlin's Temple
Vanquished the Ancient Dragons of Destruction
Wielded the Mysterious Amulet
Showed thine worst enemy, the abomination known as "The Darkness," who is the nerdiest of them all
Killed a flying enemy with a thrown Tediore weapon
Collected 10 pictures of Moxxi in Campaign of Carnage
Opened the chest at the bus stop in Fyrestone
Discovered all named locations in Eridium Blight, Arid Nexus, and Sawtooth Cauldron
Discovered all named locations in The Highlands, Thousand Cuts, and Wildlife Exploitation Preserve
I can't even capture it on my camera
Discovered all named locations in Sanctuary, Opportunity, and Lynchwood
Discovered all named locations in Three Horns, Tundra Express, and Frostburn Canyon
Killed Donkey Mong
Fed thy noble queen 3 times during one visit to her quarters
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
Completed the mission "Long Way To The Top"
Had Purple-rated gear or better equipped in every slot
Revived someone from "Fight for Your Life!" that is on your friends list
Got an item from Michael Mamaril
Killed a Chubby
Defeated Terramorphous the Invincible
Completed the mission "Shoot This Guy in the Face"
Reached level 50
Completed the mission "X Marks the Spot"
Slew Mister Boney Pants Guy
Defeated Jack
Completed the mission "Data Mining"
Completed the mission "Toil And Trouble"
Reached level 25
Completed 20 side missions
Completed the mission "Where Angels Fear To Tread"
Completed the mission "The Man Who Would Be Jack"
Completed the mission "The Once and Future Slab"
Completed the mission "Wildlife Preservation"
Gave Claptrap a high five
Tipped Moxxi $10,000
Completed the mission "Bright Lights, Flying City"
Killed 100 enemies with the Sabre turret
Completed the mission "Rising Action"
Completed the mission "A Train To Catch"
Killed a Constructor without it ever building another bot
Completed the mission "A Dam Fine Rescue"
Purchased 5 items from the black market
Reached level 10
Completed the mission "Hunting The Firehawk"
Completed the mission "Plan B"
Completed the mission "The Road To Sanctuary"
Completed the mission "Best Minion Ever"
Reached level 5
Redeemed 25 tokens
Completed the mission "My First Gun"
Unlocked 10 customization items
Complete level 1 of all non-level-specific challenges with a single character
Allow a Goliath to level up four times before killing him
Discover all named locations
Phaselock 100 enemies
Gunzerk continuously for 90 seconds
Remain in Zero's Deception mode for ten seconds straight
Complete all side missions
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".
Defeated the Dark Web.
Activated the Backburner's firewall.