Andre Chambers, 34, of Woolwich in south-east London, had evaded detectives for three years before his capture, and admitted the charges at Croydon Crown Court on Friday July 28, according to the Met.
Chambers, of Harlinger Street, had earlier pleaded guilty to possessing a firearm, possessing ammunition without a certificate and two counts of having class A drugs with intent to supply.
In September 2013, officers found a hidden 9mm Glock handgun, eight bullets and hundreds of grams of high-purity cocaine at a property in Southwark that Chambers was living in.
Forensic analysis found it was used to murder 24-year-old Errol Davis at a nightclub near London Bridge in 2008. It was also linked to the murder of 25-year-old Larry Safie in East Dulwich in 2009.
It was further found to have been used in two attempted murders in both 2007 and 2009.
Scotland Yard said Chambers did not commit the killings, but was holding the gun for other gang members.
A man was arrested and charged over the murders of Safie and Davis but was acquitted following a trial. Inquiries continue in both investigations, the Met said.
Chambers was caught in a minicab near Woolwich Ferry in October last year, more than a year-and-a-half after a £20,000 reward was offered for information on his location.
Acting Detective Inspector Martin Thorpe said a “dangerous man” was off the streets following the three-year hunt.
He added: “Chambers did everything he could to evade capture and no doubt got complacent and thought he had got away with the offences committed in 2013.
“I hope his sentence serves as a warning to those intent on concealing weapons and dealing drugs, we will continue to pursue you no matter the length of time.”