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 pyromancies.
Acquire all rings.
Acquire all sorceries.
Acquire all miracles.
Reach "To Link the First Flame" ending.
Learn all gestures.
Reach "The Usurpation of Fire" ending.
Reach "The End of Fire" ending.
Perform all forms of infusion.
Discover Mound-makers covenant.
Defeat Nameless King.
Reinforce a bonfire to the highest level.
Discover Warrior of Sunlight covenant.
Defeat Champion Gundyr.
Reinforce the Estus Flask to the highest level.
Defeat Lothric, Younger Prince, Lord of Cinder.
Defeat Dragonslayer Armour.
Reinforce any weapon to the highest level.
Defeat Ancient Wyvern.
Reach Archdragon Peak.
Reach the Untended Graves.
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.
Discover Aldrich Faithful covenant.
Discover Blade of the Darkmoon covenant.
Defeat Old Demon King.
Discover Rosaria's Fingers covenant.
Defeat Pontiff Sulyvahn.
Discover Watchdogs of Farron covenant.
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.
Defeat Vordt of the Boreal Valley.
Discover Way of Blue covenant.
Become a Host of Embers for the first time.
Defeat Iudex Gundyr.
Light a bonfire flame for the first time.