Wyman told Collider that he knows "word for word" how the series ender will go.
"I am writing and directing it, so I know exactly what it is," he explained. "It's important - as important as it is to the fans, it's important to me. I just want it to be perfect.
"I know for sure that, at the end of it all, when it's done, I will stop at nothing to make sure it's exactly as I envisioned it... because I want to deliver something that I'm proud of."
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The showrunner described the Fox sci-fi drama's final three episodes as a "continuance" of the same story arc.
"It's basically a three-hour [finale] - they're not [airing] on the same night, that's all," he said. "But it's a continuance - a lot of the story wraps up in those three episodes at the end."
Wyman recently told Digital Spy that he does not expect Fringe to continue past the finale, explaining that a spinoff or movie version is possible, but unlikely.
"It's the end of this saga," Wyman said of season five. "You never know... but as far as this story and this saga [is concerned] - it's over."
The final season of Fringe will premiere on Fox in the US on September 28 and will air on Sky1 in the UK.
Watch the cast of Fringe discuss the final season with Digital Spy below: