Robertson has struggled to regain his top form after World Championship glory in 2010 but he showed great form to take the glory in Poland.
The Australian won seven matches at the Arena Ursynow, finishing with a commanding win over Chester-based Walden.
"I couldn't have had a tougher draw as I've beaten the likes of Peter Ebdon, Stephen Maguire and Shaun Murphy to reach the final," said Robertson, who has now won a tournament carrying ranking points in each of the last six years.
"I had been on a good run of form recently with a couple of semi-finals and I was really disappointed to lose in the semis of the Shanghai Masters.
"That was a wake up call because you have to be efficient in the final stages of tournaments. It's all about winning them because that's what you'll be remembered for. So I'm really pleased to convert this one.
"The PTC events are tiring and you have to really keep your concentration, so when I got the semis I made sure I knuckled down and stayed focused."
Robertson, who moves up one place in the world rankings to fourth, believes there is potential for snooker to grow in Poland.
"The crowds have been fantastic in all of my matches," he said.
"That makes it easier to play because it gives you a buzz, and hopefully the people who came will go away with good memories.
"In Germany it took a few years for the support to grow and now we have a full ranking event there, so hopefully something similar can happen in Poland."
Earlier in the semi-finals, Walden claimed a 4-3 win over Steve Davis, who had enjoyed an inspired run to the latter stages and Robertson easily saw off Stephen Lee 4-0.