The hosts were out of sight after 34 minutes as a brace from Kevin Volland, separated by Charles Aránguiz's volley from distance, ensured the game was all but won inside the first-half.
Winger Julian Brandt completed the rout with a close-range finish from a quick free-kick to ensure Leverkusen earned all three points and moved up to 12th in the Bundesliga.
Herrlich's first win of the season a commanding one
Herrlich made three changes to the side that lost 3-1 at Mainz 05 last weekend with Lars Bender, Kai Havertz and Panagiotis Retsos replacing Jonathan Tah, Admir Mehmedi and Benjamin Henrichs.
Freiburg meanwhile made two changes to the side that held Borussia Dortmund with 10 men last week as the suspended Yoric Ravet was replaced by Nicolas Höfler while Vincent Sierro made way for Florian Niederlechner.
Die Werkself started the game the brighter side and dominated possession early on, but it took almost 20 minutes before they saw their first chance on goal as Havertz volleyed Wendell's cross wide.
The hosts opened the scoring via Volland's first goal of the season 21 minutes in, as the German forward picked up Aránguiz's pass before setting himself and blasting into the top left corner from 20 yards.
The goal was no more than Bayer 04 deserved after dominating proceedings early on, and they doubled their lead nine minutes later as Aránguiz turned from provider to finisher.
The Chilean midfielder picked up a loose ball on the edge of the box and with his first touch hammered the ball into the bottom left-hand corner to doubled Leverkusen's advantage with his first of the season.
Herrlich's side were in the ascendancy and wasted no time in trying to extend their lead even further, with Havertz's volley almost deflecting in off Phillipp Lienhart but for Alexander Schwolow's save.
Leverkusen made it three 11 minutes before half-time with Volland's second of the game, although this goal was much easier for the German as he prodded home Bender's pull-back across the six-yard box.
Brandt gets in on the action with his first of the season
Havertz almost got his name on the scoresheet as he burst into the box from the left-wing and saw his shot blocked by Schwolow at the near post, although passing may have been a better option with several black shirts arriving in the box.
Marco Terrazino should have restored some pride for Freiburg just after half-time with their second shot of the game but could only fire wide from the edge of the area, spurning Breisgau-Brasilianer's first decent opportunity of the game.
The hosts continued to create chances throughout the second period, with Karim Bellarabi going close on a couple of occasions although he couldn't keep his efforts low enough to trouble Schwolow.
Volland thought he had a hat-trick 70 minutes in as he nudged Çağlar Söyüncü off the ball and volleyed home from close range, but the goal was chalked off thanks to the video assistant referee following complaints of a foul from various Freiburg players.
Brandt capped off a fine display four minutes from time as he ghosted behind the Freiburg centre-backs and was found by Aránguiz's quick free-kick, before slotting past Schwolow for his first of the season.