The 63.79m (209ft) Stronardon Douglas fir near Dunans Castle beat the Grand Fir at Blair Castle in Perthshire to the title by more than a metre.
Organiser Mark Tansley said: "Scotland has excellent growing conditions, such as a damp environment and deep valleys that allow conifers to reach extraordinary heights."
The UK's previous tallest tree, the Douglas fir at Reelig Glen, Inverness is 62.02m, and a Douglas fir at The Hermitage, Dunkeld, Perthshire is 61.31m.
Tree climber Chris Hunter said: "I've been climbing trees for 17 years and have never tackled anything so tall, challenging and rewarding. They were truly breathtaking trees set in breathtaking locations. Every one was worth the visit on its own."