The Northern Irish player, who has slipped to 78th in the world rankings, carded four birdies in his two-under round at a windswept Castle Stuart.
"I'm really happy with that round - it was a battle out there at times," said the 2010 US Open winner.
"It would be great for my confidence to play well here."
McDowell, who won the event in 2008 at Loch Lomond, has struggled this season and missed the cut at the recent French Open.
He spent last weekend playing two practice rounds at Royal Troon, where he will compete next week at the Open.
"Those two days at Troon have been a big help and prepared me well for the wind," added McDowell.
"It it continues to blow it's going to be a real grind so I need to hang in there.
"It's been a funny year for me. It has looked volatile from a results point of view but I've felt I've played better than that.
"I'm just trying to stay relaxed and to enjoy it."
Meanwhile, Belfast man Michael Hoey started his challenge with a 74.
Graeme McDowell was pleased with a first-round 70 at the Scottish Open, which left the former champion just one shot off the lead.