Antonsson hit a winner for Rovers in their win over Scunthorpe, his second win in as many games.
Mowbray is delighted with the Swedish striker and believes he is just getting started.
Speaking to Blackburn's official website, Mowbray said: "I'm delighted for him because he works his socks off for the team.
"The goal was what we had been talking to him about, not getting across the front of the defenders, standing off the back.
"The defender didn't want to touch him and he finished it. He has lots still to improve on in his game, but it is great that he has scored some goals and great for his confidence.
"Hopefully he'll keep on getting better."
Confidence is what Antonsson needs after a lack of faith under his coaches at Leeds United.
Garry Monk did not give him a chance to establish himself as a regular after the opening month to the 2016/17 season, frequently leaving him out of the squad and with the under-23s.
By time Thomas Christiansen arrived this summer, Antonsson's confidence had taken a hit, and the new manager deemed him expendable.
Antonsson had a strong record in the Swedish league before he signed for Leeds from Kalmar.
If he carries on performing well for Blackburn who sit one point outside the play-off positions, he could well return to Leeds as a useful asset.