Police carried out a drugs warrant at a flat in Woodside Road, Sutton, on Tuesday, 9 August.
Officers forced entry to the address and carried out a thorough search of the premises.
They seized a quantity of suspected herbal cannabis from under a bed and a bag of suspected heroin hidden near a window.
A man aged in his early 20s, who was inside the rented property at the time of the raid but does not reside there, was arrested on suspicion of possession of Class A and Class B drugs. He has been taken to a South London police station. Enquiries are continuing.
The operation was led by officers from Sutton North Safer Neighbourhoods Team acting on information they received from members of the local community.
PC Stuart Ansell, of Sutton North SNT, who led the operation, said: “We want to send out a message that drugs activities will not be tolerated in this borough.”
He urged residents to contact police on 101 if they suspected an address in their area was being used for drug cultivation, dealing or supply or 999 in an emergency.
“We take all such reports seriously and we will take action to make your street and neighbourhood safer,” added PC Ansell.
Police have arranged for two cats found in the address to be watered, fed and collected by the landlord later today and put into the care of the RSPCA as the tenant is not currently residing at the address.