Police Scotland are hunting four men believed to have been driving a dark Audi found abandoned near the hotel in Auchterarder, Perth and Kinross, after the incident at the Mappin & Webb outlet at about 11am this morning.
Officers said no-one was injured but a window display was reportedly smashed and “a quantity of watches” stolen.
Mappin & Webb has two stores within the hotel which sell a “selection of premium fine jewellery and is home to the world’s most prestigious Swiss watch brands including Rolex”, according to the jeweller’s website.
Nearby residents reported seeing a police helicopter circling the hotel and surrounding area shortly after the robbery. Armed officers and police dogs were also involved in the search response.
Police taped off the entrance to the hotel and armed police were seen outside Gleneagles railway station.
Detective Chief Inspector Andy Patrick said police were taking the “shocking but thankfully rare incident” very seriously.
“Our enquiries so far have established that the individuals involved were believed to be armed but thankfully nobody has been injured, although they are understandably shaken.
“We are appealing for anyone who was in the area at the time to come forward and speak to us.
“In particular, we are looking to speak to anyone who saw a dark-coloured Audi with four men in the area around the time of the incident.
“Officers remain at the scene this afternoon to conduct enquiries, including forensic examination and we would like to reassure the public that this appears to be a targeted incident.
“Staff and residents were evacuated for a short time but have since been able to return into the hotel.
“Anyone with information is asked to contact Police Scotland on 101 quoting reference 1166 of 27/06 or Crimestoppers on 0800 555 111 if you wish to remain anonymous.”
Rooms at the famous five-star hotel cost from about £400. It is popular with golfers, having hosted the Ryder Cup in 2014.
A statement from Gleneagles said: “We are working closely with Police Scotland in relation to a robbery at the hotel this morning. We can confirm no guests or members of staff were harmed as a result of the incident. As this is an ongoing police investigation, we are unable to provide further information at this stage.”