Gallacher, Lee Westwood, Ian Poulter and will be Europe's three wild card picks for the Ryder Cup at Gleneagles, captain Paul McGinley has announced.
That meant there was no place for former world number one Luke Donald as Europe look to claim an eighth win in the last 10 stagings of the biennial contest against the United States on September 26-28.
Westwood has made eight consecutive appearances since making his debut in 1997, winning 21 points from 37 matches.
The 41-year-old finished seventh in the Masters in April and won in Malaysia the following week, but suffered a slump in form until a final round of 63 in the WGC-Bridgestone Invitational in August.
He also shared the lead after the first round of the US PGA Championship before finishing 15th, but failed to advance beyond the first FedEx Cup play-off event.
Gallacher came agonisingly close to securing an automatic place on the team by finishing third in the Italian Open on Sunday, just one shot out of the share of second place he required.
However, McGinley stayed on in Turin after missing the cut and witnessed the Scot card a flawless closing 65 to record his 10th top-10 finish of a qualifying campaign which also saw him retain his Dubai Desert Classic title in February.
Poulter has earned the nickname 'Mr Ryder Cup' and it is hard not to see why. This is the third time he has needed a wild card to make the team, but he has raised his game on every occasion and none more so than at Medinah in 2012.
The 38-year-old won all four of his matches and famously birdied the last five holes alongside Rory McIlroy to beat Jason Dufner and Zach Johnson in the Saturday fourballs. He also beat Webb Simpson in the singles to take his record to an amazing 12 wins from 15 matches.