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