A 50-year-old Brighton man was arrested on suspicion of having drugs with intent to supply at a house in Gloucester Road.
Sussex Police raided the house at around 2.30pm yesterday.
They seized 7kg of what is believed to be ketamine and more than £60,000 in cash.
Police believe that the drugs were intended for sale at Pride today and the total haul would have had a street value of about £140,000.
Chief Inspector Laurence Taylor said: “We are taking a robust stance on drug misuse at Pride.
“This haul has made a significant dent in the illegal drugs trade surrounding the event.
“Last year St John Ambulance dealt with a number of casualties as a result of ketamine.
“We will not tolerate drug use at Pride or other events in the city, hence our action yesterday carrying out this raid.”
Earlier today the suspect was still in custody awaiting interview.
