Full list of all 63 Hollow Knight achievements. It takes around 60-80 hours to unlock all of the achievements in the base game on Windows.
The base game contains 52 achievements, and there are 3 DLC packs containing 11 achievements.
Rescue half of the imprisoned grubs
Acquire half of Hallownest's Charms
Defeat the Dung Defender
Acquire 4 Mask Shards
Destroy Herrah the Beast
Defeat the Broken Vessel
Acquire 3 Vessel Fragments
Open half of Hallownest's Stag Stations
Defeat the Soul Master
Defeat Hornet in Greenpath
Defeat the False Knight
Acquire your first Charm
Acquire all Charms and receive Salubra's blessing
Acquire all Mask Shards
Acquire all Vessel Fragments
Defeat the Failed Champion
Defeat Hornet in Kingdom's Edge
Defeat the Lost Kin
Defeat the Mantis Lords
Defeat the Collector
Defeat Zote in the Colosseum of Fools
Collect 600 Essence
Collect 1800 Essence and awaken the Dream Nail
Collect 2400 Essence and hear the Seer's final words
Rescue all of the imprisoned grubs
Leave Zote to die
Slay the Nailsmith with the Pure Nail
Allow the Nailsmith to find a new calling
Spend a final moment with Quirrel
Bring peace to the Grey Mourner
Defeat the Traitor Lord
Open all of Hallownest's Stag Stations and discover the Stag Nest
Destroy Monomon the Teacher
Destroy Lurien the Watcher
Acquire a map of each area
Complete the Trial of the Warrior
Complete the Trial of the Conqueror
Complete the Trial of the Fool
Defeat the Hollow Knight and become the Vessel
Defeat the Hollow Knight with Hornet by your side
Defeat the Radiance and consume the light
Remember the past and unite the Abyss
Complete the game in under 10 hours
Complete the game in under 5 hours
Achieve 100% game completion and finish the game
Achieve 100% game completion and finish the game in under 20 hours
Finish the game in Steel Soul mode
Achieve 100% game completion and finish the game in Steel Soul mode
Record all of Hallownest's creatures in the Hunter's Journal
Receive the Hunter's Mark
Aid the Herald in moving on
Defeat the Soul Tyrant
Defeat White Defender
Defeat Grey Prince Zote
Defeat Troupe Leader Grimm
Defeat the Nightmare King and complete the Ritual
Banish the Grimm Troupe from Hallownest
Complete the Pantheon of the Master
Complete the Pantheon of the Painter
Complete the Pantheon of the Sage
Complete the Pantheon of the Knight
Ascend the Pantheon of Hallownest and take your place at its peak
Achieve 112% game completion and finish the game.