Then they joined in various activities and training sessions throughout the afternoon with children from the local rugby clubs led by Ulster Branch development staff.
In what was a milestone event for Donegal, this was the first time that the full Ulster squad had taken part in such an event outside of Belfast.
Children from Letterkenny, Donegal Town, Ballyshannon and Inishowen Rugby Club took part in the activities at Letterkenny RFC, and the afternoon ended with Ulster players signing autographs for the excited children and interacting with club coaches and parents.
Later that evening, the Ulster players and managers were invited to a reception at the Radisson Hotel in Letterkenny where they met volunteers from the local rugby clubs and members of the Donegal Project.
Speeches were made by Graeme Cattermole, Chairman of the Donegal Community Rugby Project, as well as Matt Williams and Rory Best.
Speaking about the benefit of the Ulster squad's visit to Donegal, Graeme Cattermole said: "I would like to express my sincere thanks to Matt Williams and his entire Ulster squad and management for coming to Letterkenny and lending their support to the Donegal Community Project.
"The event has highlighted the work of the Project, which has seen rugby expand in Donegal at a very fast pace over the past two years.
"More and more young people are turning towards the game, due to its ethos and culture which they aspire to and enjoy.
"I was particularly impressed with the attitude and the way in which all members of the squad interacted with the Donegal rugby folk, and their friendly approach and willingness to get involved was very much appreciated.
"It was very clear that the young rugby players thoroughly enjoyed the experience of mixing with the players (such as Grand Slam winners Tom Court and Rory Best pictured), and will be something that will live on with them for a very long time.
"I have no doubt that there will be more young people from Donegal making their way to Ravenhill next season to attend the Ulster home games.
"The rugby volunteers of the county from the clubs, schools and community in general also cherished the opportunity of meeting the squad at the evening Reception."
The Donegal Community Rugby Project, which was founded in September 2007, was set up to encourage the development and growth of rugby across Donegal.
Over the past two years, interest in the sport has reached a phenomenal level, and with the added support of the Ulster squad rugby fever in Donegal looks set to reach an all-time high.
For further information on the Donegal Community Rugby Project, please visit http://www.donegalcommunityrugby.com