Former world champion Robertson looked to be on his way out of the competition after falling 2-0 down to Ding in what was a straight shoot-out for a place in the final four at Spennymoor Leisure Centre.
But the Australian reeled off four games on the bounce to secure the runner's up spot in the group and set up a meeting with current world number one Judd Trump on November 24 in Grimsby.
Group B runner-up John Higgins will play Stuart Bingham, who topped Group A, in the other semi-final. The final is scheduled for the day after.
"In the first few frames I had a pretty horrible run of the ball. Tonight looked like it wasn't going to be my night but I fought back really well and capitalised on some of Ding's mistakes," Robertson said.
"But if Ding doesn't get the kick on a red in the last frame then I go out. I've missed out on making the semi-finals of the Premier League by a frame twice already, so I didn't want to make it a third time."
Earlier in the evening, Higgins lost 4-2 to Peter Ebdon to finish second in Group B.
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