Officers found the 200 plants in the upstairs bedrooms on Pot House Lane after a warrant at the address.
The plants have been seized along with lighting and cultivation equipment. Enquiries are ongoing to find out who was responsible.
PC Kat Stokes from Oswaldtwistle neighbourhood policing team said: “This was a very sophisticated set up which had clearly been going for some time. Clearly someone has been tending to the crop on a regular basis and we are carrying out forensic enquiries to find out who was responsible.”