He birdied four of his closing six holes in superb scoring conditions on the Gut Larcenhof course.
It left the Bathgate pro the highest-ranked Scot and just three strokes behind the leading duo of Australia's Marcus Fraser and Paraguay's Fabrizio Zanotti, who both carded 64s. Three players, including Ireland's Paul McGinley, recorded 65s.
McGinley, who is favourite to captain Europe at the Ryder Cup in two years time, posted his best opening round in seven years, making an eagle at 16, par at 17 and a birdie at the last.
It is the third time this year that Gallacher has posted a sub-70 opening round in 11 Tour events this year. In those other tournaments – the Dubai Desert Classic and Maybank Malaysian Open – the Scot has finished in second place.
"It could have easily been a lot lower," he said. "But while I felt as though I left a few out there, it's a good start."
Gallacher, who is still looking to capture a second Tour title since winning at St Andrews in 2004, admitted he has always enjoyed a profitable return when given an early tee-time. "I like playing early in the day," he said. "I'm usually up early around 6.30am when I'm at home and this morning I was up at 5am so I don't mind the early starts."
This week heralds the start of a busy run of events for the 37-year-old, as he bids to make his way into the Open Championship. On Monday, Gallacher will be among seven Scots teeing-up at an Open qualifier at Sunningdale, with the leading 10 players from winning through to Royal Lytham and St Annes.
He is then due to contest the Irish Open, French Open and then a Paul Lawrie corporate outing at Skibo Castle ahead of the Scottish Open. "These weeks can either make or break your season," he added.
Colin Montgomerie and Stephen O'Hara posted 69s, meanwhile, as David Drysdale slipped to a share of seventh. Paul Lawrie posted a 72.