oel Osei, 25, and his partner, Diana Cristea, 19, used Grindr to befriend men before drugging and robbing them.
Jurors at Croydon Crown Court heard the couple targeted gay men on the app in order to rob them of their money and valuables.
Osei was jailed at the same court for a minimum of 32 years.
Mr Murphy's body was discovered in his Battersea flat by his best friend on 4 June 2019.
Toxicology reports showed he died from an overdose of scopolamine - a substance commonly used in rapes and kidnappings in South America.
After killing the 44-year-old, the couple attempted to buy $80,000 (£62,000) worth of diamonds from a jeweller in New York, the court heard.
Osei, of Seven Sisters, and Cristea, of Mill Hill, were also involved in the poisoning of a second man with the same drug two days earlier, jurors were told.
The victim, who cannot be named for legal reasons, survived but was taken to hospital after being found by a neighbour almost naked, extremely agitated and confused.
Items including his wallet, bank cards and two laptops worth about £2,000 were stolen.
Osei used the same phone number to contact both victims and was later identified by the surviving man.
Analysis of Osei's phone and laptop linked Cristea to the crime and revealed he bought the scopolamine online in early May 2019.
Jailing Osei for life on Friday, Mr Justice William Davis said the pair "left Mr Murphy for dead".
He said: "You gave Mr Murphy, quite deliberately, a significant dose of a drug which you know could cause death."
Osei was given a concurrent sentence of five years in prison for administering a poison or noxious substance so as to endanger life against the surviving victim, and no separate penalty for multiple counts of theft and fraud.
Cristea, who was convicted of the same offences, will be sentenced at a later date.