Sebastien Buemi and Antonio Felix da Costa will make up Red Bull Racing's test and reserve driver line-up for next season.
After losing his race-seat with junior team Toro Rosso, Buemi joined Red Bull as a test driver in 2012, mixing his team duties with sportscar racing.
His extended World Endurance Championship programme in 2013 saw da Costa given the opportunity at Red Bull as he substituted for the Swiss driver on several occasions.
Da Costa also took part in the 2013 Young Driver outing and took third place in this year's Renault 3.5 series with three wins to his name.
The duo will share the test and reserve drivers duties for Red Bull next year.
"It's great to be able to announce the signing of Sébastien and António for 2014," said team boss Christian Horner.
"Next year sees the biggest change to the Formula One regulations for some time and the return of multiple in-season tests. To therefore be able to call on two such capable drivers is of huge benefit to the team.
"In Sébastien we have a great resource, a driver with extensive grand prix experience and that will be invaluable.
"António, on the other hand, is an up-and-coming talent with whom we already have a good working relationship. I'm sure that his contribution will be just as important during what is sure to be an intensely busy season."