Airport employees Vaughn Henry, 46, of Church Road, Willesden, and Dev Anand, 24, of Willoughby Road, Slough, worked together to collect a bag containing “high-purity cocaine” at the airport.
The bag, containing around three kilos of the Class A drug, arrived on a flight from Brazil to Heathrow's Terminal 3 on February 5 this year.
Henry was sent pictures of the bag by London-based drug trafficker Grattan Samuels, 23, of Old Ford Road, Victoria Park, who was in contact with other criminals and organised the importation.
Anand, 24, then picked up the bag from the flight and gave it to Henry to store in his staff locker until his shift finished.
That evening, Henry handed the bag to taxi driver Adnan Ahmed Malik, 24, of Paignton Road, Birmingham, who was waiting outside Heathrow for the bag.
Malik's job was to transport the drugs to Birmingham, but officers from the National Crime Agency arrested him before he could set off.
Samuels and Anand were arrested by the NCA in April, after Whatsapp messages and photos on Henry's phones linked them to the crime.
The pair later pleaded guilty to conspiring to import drugs, but Samuels also admitted a separate charge of conspiring to acquire a firearm.
Henry and Malik denied the charges, but following an eight-day trial at Birmingham Crown Court, they were both found guilty on October 18.
All four men will be sentenced at the same court on November 3.
Colin Williams, NCA branch operations manager, said criminals like Henry and Anand can expect their officers' “full attention”.
“Henry and Anand used their privileged access to Heathrow for criminal purposes, offering a crucial service to drug traffickers and bypassing border controls,” he said.
“Tackling corruption at the border is a major priority for the NCA and our law enforcement partners – it threatens the safety and security of the UK.
“People like Henry and Anand who use their employment to engage in organised criminality can expect our full attention.”