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.
Acquire all rings.
Acquire all miracles.
Acquire all sorceries.
Acquire all pyromancies.
Reach "The End of Fire" ending.
Reach "The Usurpation of Fire" ending.
Learn all gestures.
Defeat Crystal Sage.
Discover Mound-makers covenant.
Reach "To Link the First Flame" ending.
Defeat Nameless King.
Perform all forms of infusion.
Defeat Lothric, Younger Prince, Lord of Cinder.
Reinforce the Estus Flask to the highest level.
Reinforce a bonfire to the highest level.
Defeat Ancient Wyvern.
Discover Aldrich Faithful covenant.
Reinforce any weapon to the highest level.
Reach Archdragon Peak.
Defeat Champion Gundyr.
Reach the Untended Graves.
Defeat Oceiros, the Consumed King.
Defeat Dragonslayer Armour.
Defeat Yhorm the Giant, Lord of Cinder.
Defeat Aldrich, Devourer of Gods, Lord of Cinder.
Discover Blade of the Darkmoon covenant.
Defeat Pontiff Sulyvahn.
Defeat Old Demon King.
Defeat High Lord Wolnir.
Discover Rosaria's Fingers covenant.
Defeat Dancer of the Boreal Valley.
Defeat the Deacons of the Deep.
Defeat the Abyss Watchers, Lords of Cinder.
Discover Watchdogs of Farron covenant.
Discover Blue Sentinels covenant.
Discover Way of Blue covenant.
Discover Warrior of Sunlight covenant.
Defeat the Curse-rotted Greatwood.
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.