Here is the full list of all 61 Sifu achievements.
The base game contains 51 achievements, and there is 1 DLC pack containing 10 achievements.
Clear all tiger arena challenges.
Clear all dragon arena challenges.
Collect 240 stamps in arenas.
Clear any challenge of the Heliport arena by throwing all enemies out.
Finish the target with a snowball in the "Cyclone" arena challenge.
Throw the Disciple in the lake in the "Bellowing Mountains" arena challenge.
Clear an arena challenge with the Custom Mode enabled.
Attempt to clear any level with the Modifiers Randomizer enabled.