The 70-kilo dog called Magnum was part of a delegation from Switzerland which met with Pope Francis in St Peter's square in Vatican City following his weekly audience, reported news agency ATS.
Magnum was accompanied by staff from the Barry Foundation in Martigny, a non-profit organization which aims to ensure the survival of the famous Swiss breed which has long been associated with rescue work in the mountains.
Since 2005 the foundation has operated the 300-year-old breeding kennel on the Great Saint Bernard Pass between Switzerland and Italy.
The Swiss group was in Rome to liaise with Italian Unesco representatives over an application the Swiss-Italian Great Saint Bernard region is making for Unesco World Heritage status.
The legendary Swiss dog breed is one focus of its application, along with the male choir of the Great Saint Bernard hospice and the alpine passes in the region.
The aim is to gain recognition for the region's history and culture, Swiss politician Christophe Darbellay, who was part of the delegation, told ATS.
Pope Francis spent time patting Magnum and chatting with his handlers.
“The pope loved this gentle giant,” said the Barry Foundation's president Claudio Rossetti, though some papal disappointment was expressed that Magnum wasn't wearing a traditional barrel around his neck.
“We explained that the dog was still too young to wear it,” said Rossetti.
Back in Switzerland, Swiss heritage organization Schweizer Heimatschutz (SH) on Wednesday called for Unesco to inscribe the historic Gotthard train line on its World Heritage list.
The original Gotthard line opened in 1882 and is an important rail link between northern and southern Europe.
In June the opening of the new Gotthard base tunnel will bypass part of the traditional high route, leaving many to wonder what will become of it now.
The government has previously decided against submitting it for Unesco candidacy but in a statement on Wednesday SH disagreed.
The line is “one of the most striking embodiments of Swiss identity” and deserves to be placed under Unesco protection, it said, calling for an application to be lodged right away.
Switzerland currently has 11 sites on the Unesco World Heritage list, which will this year be celebrated with special events on the weekend of 11-12 June.