Keith Chapman of Lowmill Landscapes in Finghall, North Yorkshire, and Tim Lancaster, who works for Leeds-based RMP Properties, won the medallions after rising to the competition challenge of building a landscape garden.
The prestigious event is held every other year and this year was held over four days in November.
The pair's efforts helped the UK team, made up of some 22 skilled young people representing different industries, reach 11th out of the 49 nations that took part.
Innovation, Universities & Skills secretary of state John Denham said: "To have achieved such great results proves we have skills in this country at world-class levels."
Team member Natalie Stanyer, also 21, won a medallion in the floristry part of the event. The medallion ranks after the bronze medal in the competition.
Chapman and Lancaster both trained at Askham Bryan College in York, gaining the National Diploma in horticulture apprenticeship.
The pair won the landscape part of the UK Skills competition in 2005 to qualify for a place on the national team and were accompanied by their landscape lecturer Harry Turner.
UK Skills chair and UK Commission for Employment & Skills chief executive Chris Humphries said: "These 22 young UK competitors rose to the challenges presented by the WorldSkills Competition and confirmed that they are true champions. Everyone at UK Skills offers their heartiest congratulations to them and their trainers."