The defendant yelled an expletive after the sentence was pronounced.
Authorities and Minor both say Locker asked for help staging his death to look like a robbery, so his family could collect insurance money.
Prosecutors said Minor went beyond aiding suicide by stabbing the 52-year-old Locker seven times in the self-help expert's car.
Minor said he only held a knife while Locker repeatedly lunged into it.
Locker, who co-authored a 1998 self-help book and gave presentations on handling workplace stress. But he was deep in financial trouble himself, partly because of his investment in a $300 million Ponzi scheme run by Backstreet Boys and 'N Sync mastermind Lou Pearlman.
Minor was a down-and-out stranger, a former computer technician with a record of drug arrests. He said he initially balked at Locker's request but started to feel sorry for him after hearing about his money troubles.
"This was murder for money, not a mercy killing," Manhattan District Attorney Cy Vance Jr. said after Minor's conviction last month.
"He was taken advantage of. ... He's no contract killer," his lawyer, Daniel J. Gotlin, said in his closing argument. He has said Minor plans to appeal.
Locker's family has been unable to collect most of the insurance money. His widow, Lois, said in a statement last month after the verdict that it would "be good to put this part of the healing process behind us."
Criminal cases surrounding assisted suicide have often concerned terminally ill people and the medical providers or relatives who help them end their lives. But a few other cases besides Minor's have involved looser relationships and people who weren't sick.