A search warrant was executed under the Misuse of Drugs Act at the house in Regent Terrace yesterday.
Officers found 42 cannabis plants and growing equipment inside a first floor bedroom.
North Yorkshire Police said the street value of the plants was yet to be confirmed, but it is believed to be in the thousands.
Two men from Harrogate, aged 49 and 36, were arrested as part of the ongoing investigation.
The 36-year-old was arrested on suspicion of cannabis production and the 49-year-old on suspicion of possessing cannabis with intent to supply.
Both men have been released while under investigation.
Sergeant Joe McAvoy, of Harrogate Police, said: “Drug use is a blight on our communities and won’t be tolerated.
"If you have information about drug production or dealing in your neighbourhood, please let us know. Every small piece of information helps to build up a bigger picture so we can take action.”
Anyone with information on drug dealing in their community is urged to call police on 101.
Information can also be passed on anonymously via Crimestoppers on 0800 555 111.