The team picked up three race wins and six further podiums at the hands of Max Verstappen, who ended the season third in the drivers' standings.
Horner praised the Japanese manufacturer for its deliverance of a strong power unit this year, hailing its improved reliability and performance.
"I think it really has been beyond expectations in many respects," Horner said. "The relationship with Honda has been fantastic, the reliability, the performance, the increase with each engine has been very much the highlight."
Horner admits that he was left impressed by the displays of Verstappen this year, who took part in his fourth year with Red Bull.
"I think the way that Max has driven as well has been very, very positive. We obviously had the driver change halfway through the year, and I think that was the right thing to do.
"Alex got a seat in the car for next year and we go into the winter on the back of a very promising result here in Abu Dhabi with a lot of motivation."
Verstappen was heard over the race explaining about 'turbo lag', which Horner affirmed didn't change the outcome of the 22-year-old's race.
"He picked up a bit of turbo lag after the pit stop, we’ll investigate why that happened," Horner said. "You could hear the switch changes that were going on to try and help it.
"It was just not optimal for Max wanting to get the performance out of the car. The turbo lag interrupts your rhythm over a lap. The result would have been the same."
Bahrain International Circuit - Winter testing