Law never actually joins the Straw Hats as an official crew member in the canon story; he remains the captain of his own Heart Pirates and is Luffy’s ally rather than a Straw Hat.

What does happen in the anime is:

  • Luffy and Law first properly connect as allies during the events around Punk Hazard and Dressrosa.
  • The formal pirate alliance between Luffy and Law is formed in Episode 594 , titled “Formed! The Luffy-Law Pirate Alliance!”

So if you’re searching “what episode does Law join the Straw Hats,” the closest canon answer is:

He does not join the Straw Hats as a member, but he forms an alliance with them in Episode 594.

Many videos and fan discussions online talk about “Law joining the Straw Hats,” but those are theories, edits, or speculative content, not canon events from the anime or manga.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.