Liverpool ended the campaign on 99 points, 18 ahead of nearest rivals Manchester City while Newcastle finished 13th on 44 points.
Liverpool went behind to the fastest goal ever scored against them in the Premier League era as Dwight Gayle latched on to Jonjo Shelvey's free kick and slotted it past Alisson with 26 seconds on the clock.
With Liverpool having made five changes to the team that started the 5-3 win over Chelsea on Wednesday, it fell to ever-present Virgil van Dijk to score the equaliser with a towering header seven minutes before halftime.
"It's far away from being perfect, but it's a good example for what the boys did over the whole season," Klopp said of the comeback win.
"They didn't only win football games when the sun is shining, the pitch is perfect, the ball, everything is perfect. They won all the difficult games -- not all of them, but a lot of them -- and today was a difficult game.
"We won it, well-deserved, They competed 95 minutes in the game, after the season the boys played? Incredible, really," he added.
Origi, who had not scored in the league since bagging a brace against Everton on Dec. 4, put the Reds in front in the 59th minute, cutting in from the left before curling the ball in at the far post.
Adopting a shoot-on-sight policy as he chased his 20th league goal of the season, Salah hit the post and it was Mane who fired home in the 89th minute to round off the season in style for the Reds.
Though delighted with the outcome of the season, defender Van Dijk said that Liverpool will have no time to rest on their laurels as the new season is set to begin on Sept. 12.
"The personal highlight is winning the Premier League. It's been a big dream for me coming true."," he told BT Sport. "I think for all of us, for this beautiful club, it's outstanding, and it should spur us on to try even harder to retain the title.
"We knew it was going to be tough, and we made it even more difficult for ourselves after I don't know how many seconds. But we played well, second half was outstanding I think. Good to finish up the season on a high."