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.
Discovered all named locations in Three Horns, Tundra Express, and Frostburn Canyon
Completed all side missions
Defeated Terramorphous the Invincible
Reached level 50
Completed the mission "The Fall of Nakayama"
Completed the mission "Long Way To The Top"
Showed thine worst enemy, the abomination known as "The Darkness," who is the nerdiest of them all
Won the most challenging round in Murderlin's Temple
Fed thy noble queen 3 times during one visit to her quarters
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
Completed the mission "X Marks the Spot"
Defeated Jack
Completed the mission "Data Mining"
Opened the chest at the bus stop in Fyrestone
Completed the mission "Toil And Trouble"
Killed a Chubby
Had Purple-rated gear or better equipped in every slot
Completed the mission "Where Angels Fear To Tread"
Killed a flying enemy with a thrown Tediore weapon
Discovered all named locations in Sanctuary, Opportunity, and Lynchwood
Got an item from Michael Mamaril
Completed the mission "The Man Who Would Be Jack"
Gave Claptrap a high five
Allowed a Goliath to level up four times before killing him
Completed the mission "The Once and Future Slab"
Reached level 25
Completed the mission "Shoot This Guy in the Face"
Completed the mission "Wildlife Preservation"
Tipped Moxxi $10,000
Completed Round 5 of any Circle of Slaughter
Completed the mission "Bright Lights, Flying City"
I can't even capture it on my camera
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"
Completed 20 side missions
Purchased 5 items from the black market
Completed the mission "Hunting The Firehawk"
Reached level 10
Revived someone from "Fight for Your Life!" that is on your friends list
Completed the mission "Plan B"
Completed the mission "The Road To Sanctuary"
Completed the mission "Best Minion Ever"
Reached level 5
Completed the mission "My First Gun"
Redeemed 25 tokens
Unlocked 10 customization items
Complete level 1 of all non-level-specific challenges with a single character
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
Phaselock 100 enemies
Gunzerk continuously for 90 seconds
Kill Donkey Mong
Remain in Zero's Deception mode for ten seconds straight
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
Collect 10 pictures of Moxxi in Campaign of Carnage
Complete all Hammerlock's Hunt side missions
Discover all named locations in Hammerlock's Hunt
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
Activate the Backburner's firewall.
Allow Tiny Tina to arm the moonshot cannon.
Defeat Haderax the Invincible.
Defeat the Dark Web.
Equip effervescent-quality gear in all slots (except class mod).
Complete the mission "Paradise Found".