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