Temitope Adeyinka, of Buxton Road in Stratford, stood trial at Woolwich Crown Court charged with murder 50-year-old Robert Powell on June 13, 2020.
Mr Powell, who left a party at an address in Water Lane, Roydon, at around 4.45am, was shot eight times and later died in hospital.
Two women were also caught in the hail of bullets and suffered serious injuries.
Adeyinka, 41, was tracked down last year in Spain following a four-year manhunt and he was arrested
He denied charges of murder and possession of a firearm.
Following the trial this year on Friday (November 7), a jury cleared him of murder and possession of a firearm, but found him guilty of manslaughter.
The trial had heard how Adeyinka, who had the street name ‘Limo’, was a long-term associate of the leader of the hit, Nana Oppong.
Learning that Mr Powell would be attending the party that night, he formed a plan with a team of co-conspirators to execute a hit.
Oppong, 45, and 41-year-old associate Israar Shah were both convicted of murder last year and jailed for life.
The leader devised the plan in an unregistered Ford Kuga while driving to the scene with support of two other vehicles.
Adeyinka and Shah, were in a Prius at the time.
This car was seen prowling up and down the road outside the party venue, the pair keeping watch for Mr Powell.
When Mr Powell emerged, the Kuga carrying Oppong pulled up near him, a gunman briefly stepped out and the murder took place.
CCTV and other evidence proved Adeyinka met up with Shah and Oppong, travelled to the party and was in contact with Oppong in the hours before and following the murder.
Enquiries continue to identify others likely involved in the plot.
Detective Superintendent Stephen Jennings, who has led our investigation for the past five years, said: “This has been a complex, difficult and lengthy investigation.
“It became clear as our enquiries began, in the aftermath of the party in Roydon, that not one person in attendance was willing to give a statement to us.
“Undeterred, we grew our investigation from a single piece of intelligence, piecing together the wider conspiracy to murder Robert Powell and identifying three key suspects.
“Adeyinka, as we saw with Oppong and Shah, tried to flee the country and spent four years on the run.
“We heard during his trial he spent his time in Marbella.
“But he would have been looking over his shoulder, and it was only a matter of time before we tracked him down with our partners abroad.
“Well away from his time enjoying sunny Spain, he will now spend his time in a prison cell for his part in this crime.
“The murder of Robert Powell was rare in its brutality and level of organisation.
“We were committed – and remain committed – to bringing all of those involved in this shooting to justice.”
