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