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