Joshna recorded a facile 13-11 11-4 11-8 win to set up the title clash against England's third seed Sarah Jane Perry, who dashed hope of an all-Indian final by getting the better of Anaka Alankamony.
Anaka went down fighting 11-8, 5-11, 11-6, 12-14, 6-11 in 69 minutes in the second semifinal.
Joshna, who had suffered a knee injury three months ago, was in her elements as her variety of shots and control was too good for the Egyptian.
Anaka fought well but it was tough for her to get to her grips against a higher-ranked rival.