Here is the full list of all 43 DARK SOULS III achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Complete all achievements.
Reach "To Link the First Flame" ending.
Acquire all rings.
Learn all gestures.
Reach "The Usurpation of Fire" ending.
Acquire all miracles.
Acquire all pyromancies.
Acquire all sorceries.
Discover Mound-makers covenant.
Perform all forms of infusion.
Discover Blade of the Darkmoon covenant.
Reach "The End of Fire" ending.
Discover Aldrich Faithful covenant.
Discover Warrior of Sunlight covenant.
Discover Rosaria's Fingers covenant.
Reinforce a bonfire to the highest level.
Reinforce the Estus Flask to the highest level.
Reinforce any weapon to the highest level.
Discover Watchdogs of Farron covenant.
Defeat Nameless King.
Defeat Lothric, Younger Prince, Lord of Cinder.
Defeat Dragonslayer Armour.
Defeat Ancient Wyvern.
Defeat Champion Gundyr.
Reach the Untended Graves.
Reach Archdragon Peak.
Defeat Oceiros, the Consumed King.
Defeat Dancer of the Boreal Valley.
Defeat Yhorm the Giant, Lord of Cinder.
Defeat Aldrich, Devourer of Gods, Lord of Cinder.
Defeat Pontiff Sulyvahn.
Defeat Old Demon King.
Defeat High Lord Wolnir.
Defeat the Abyss Watchers, Lords of Cinder.
Defeat the Deacons of the Deep.
Defeat Crystal Sage.
Discover Blue Sentinels covenant.
Defeat the Curse-rotted Greatwood.
Discover Way of Blue covenant.
Defeat Vordt of the Boreal Valley.
Become a Host of Embers for the first time.
Defeat Iudex Gundyr.
Light a bonfire flame for the first time.