The Finnish producer will supply the paper for 66 of Haymarket's 67 UK publications, which include Eve, Autocar, Management Today and PrintWeek, in a deal worth more than 13m per year.
UPM already supplied about 5m worth of paper to Haymarket a year.
The publishing company's group production director, Chris King, said UPM's commitment to service and the environment, as well as its performance during last year's mill strikes, were deciding factors in awarding it a near sole-supplier deal.
"There is a lot of dependence on one supplier, but we are a small enough publisher to make it attractive to us and to UPM," said King.
He added that Haymarket would be standardising papers and trim sizes, and introducing more environmentally sound grades.
Haymarket will also gain better price visibility as a result of the deal, said King.
"It's essential," he said. "[Rising energy costs] are going to become more and more of a factor over the next few years."
Haymarket has been consolidating its supply base in recent years.
Just before Christmas, Fresh Media Group was given sole responsibility for its repro.
Fourteen months ago, a 50m, five-year deal was signed with Wyndeham to print 45 of its titles.