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