The tickets for play on September 26 to 28 will be sold on a first-come-first-served basis from today.
Richard Hills, Europe's Ryder Cup director, said: "It's common for a small number of general admission tickets to return once the final round of commercial allocations are complete.
"Tens of thousands of people made the effort to register for Ryder Cup tickets last year, and while many were successful, many others were not. Therefore, we wanted to make these tickets available to them as well to people who perhaps hadn't registered before."
VisitScotland said there was still accommodation available near Ryder Cup park and ride locations in Stirling, Perth and Balado for those requiring an overnight stay to attend the competition.
Chairman Mike Cantlay said: "Spectators are coming from 75 countries worldwide to attend the 2014 Ryder Cup and as such accommodation pick up has been strong.
"However, there is still some accommodation available and given the central location of Gleneagles and the excellent transport links, the 2014 Ryder Cup lends itself perfectly to those even wishing to stay a little further afield and combine a trip to the event with a golfing holiday in one of Scotland's many terrific golfing regions."
The tournament takes place over six days including three practice days from September 23 to 25.
Daily tickets range in price from £10 to £145 and can be purchased online at www.rydercup.com.
Mr Hills said: "In addition to the match day tickets, tickets for the practice days are also available via the website. These days are a fantastic way to experience the occasion on a budget while still getting the chance to see the world's elite golfers up close and personal."