The hosts took control of the match following the early goal and Celtic had to thank Fraser Forster after a number of saves kept his side ahead.
Thomas Sorum had Helsingborg's best chance of the first half but the striker took too long to test Forster and Adam Matthews recovered well to clear the ball to safety.
Helsingborg continued to dominate possession in the second period and they were almost level in the 50th minute when Christoffer Andersson fired a shot that sailed just wide of Forster's goal.
However, it was Celtic who managed to find the second goal of the match when Samaras found space inside the box to head home a corner from Commons.
The Swedish side failed to recover following the goal from Samaras and Celtic nearly extended their lead when Charlie Mulgrew hit the bar with an effort from outside the area but some good defending in the final stages mean that Lennon's team are in charge after the first leg.