Dyfed Powys Police said they made the find after being called to deal with a disturbance at a building on Church Street in Knighton, just before 3.30am on Sunday, January 7.
The force said two people had been arrested on suspicion of burglary and possession of a class B drug with intent to supply.
The incident has also seen an investigation launched into the discovery of the cannabis.
A statement from the force said: “On attending, officers became aware that cannabis was being grown at the property.
“Two people have been arrested on suspicion of burglary and possession of a class B drug with intent to supply. Both have been released on bail.
“Enquiries into the cannabis cultivation are ongoing.
“Anyone with information which could assist the investigation, or anyone who has suspicions about possible illegal drug cultivations is asked to contact Dyfed-Powys Police online at https://bit.ly/DPPContactOnline or by e-mailing 101@dyfed-powys.police.uk.