The Red Bull team principal has overseen four consecutive driver and constructor championships in the past four seasons, and he praised the work done by their engine suppliers.
Changes across Formula One for the 2014 season will see each team have to use new V6 turbocharged engines while also incorporating aerodynamic changes.
Horner is confident the relationship between Red Bull and Renault will enable Sebastian Vettel and Daniel Ricciardo to remain at the front of the grid.
"Renault has got a great track record and we have achieved some phenomenal things with them," he told AUTOSPORT.
"They perhaps don't have the budget of some of the others but they have been prudent in how they spend it.
"We are pretty confident that we will have a competitive power plant.
"There's an awful lot of hearsay that goes round at this time of year but as always, what is important is what happens when the flag drops in Melbourne."
Their partnership with Renault began in 2007 and has produced 47 victories in the past five seasons.