Steve McClaren's team controlled the game from start to finish and led 2-0 at the break through early strikes by Ishmael Miller and a penalty from the impressive Lewis McGugan.
The Championship outfit did not relent in the second half and further goals from Robbie Findley and Radoslaw Majewski sealed a comfortable night, with Elliot Benyon's spot-kick a mere consolation for the hosts.
It took just three minutes for Forest to break the deadlock as Majewski's through-ball played in Miller and he comfortably slotted his first goal for his new club.
Their second goal arrived three minutes later when Miller was brought down by Wycombe goalkeeper Nikki Bull and McGugan thumped in the resulting penalty.
The visitors were rampant and nearly had another when Miller's blocked shot broke to McGugan inside the area, and he brought a fine save out of Bull.
McGugan was pulling the strings and he blasted a free-kick from fully 35 yards at Bull, who then had to parry away Miller's shot at his near post just past the half-hour.
Wycombe came extremely close to pulling one back on the hour when Kevin Betsy played in Benyon but his effort hit the inside of the post with Forest keeper Lee Camp beaten.
Two minutes later and the result was put beyond doubt as United States international Findley cut inside his marker before passing into the far corner.
The League One Chairboys had some reward when Joel Lynch conceded a penalty by tripping Stuart Lewis, and Benyon sent Camp the wrong way.
But the visitors struck again with 15 minutes left as substitute Joe Garner outmuscled Marvin McCoy before squaring it to allow Majewski to tap into an open goal.