Officers seized the drugs after conducting a warrant at an address in the High Street.
One 23-year-old man was arrested after the warrant which took place at 2pm on Saturday, and remains in custody, West Midlands Police said.
Bilston Police tweeted saying: "Our team, led by PC 27290 Lowe, conducted a warrant at an address in Hi St, Bilston, approx 400 cannabis plants seized and one arrested."
A spokeswoman for West Midlands Police said: "Drugs warrant at address on Bilston High Street, 23-year-old man arrested just before 2pm. Still in custody."