The Bees started the day in seventh needed to beat Wigan and hope Derby and Ipswich lost, the latter by a sufficient margin to overhaul the difference in three goals between the sides. Wolves had a chance of overhauling Brentford but needed to heavily outscore Millwall were the Bees to win.
Before Mark Warburton's side had even kicked off at Griffin Park, Ipswich took the lead through Daryl Murphy's sublime volley making it seem as if their efforts could well be futile.
They were handed an early boost as Derby fell behind at home to Reading through Kwesi Appiah's goal.
Wolves jumped into sixth as Nouha Dicko gave them the lead against the relegated Lions but they were not to stay there long as Brentford moved into the play-off spot thanks to Alex Pritchard's free kick on 26 minutes.
Blackburn struck back with two goals in six minutes against Ipswich with former Bee Jordan Rhodes equalising and Craig Conway gave Rovers the lead. It meant one goal for Brentford or Blackburn would move the Bees into fifth.
Derby had a chance to climb back into the top six after being awarded a penalty but Adam Federici saved from the spot.
Brentford jumped into fifth as Moses Odubajo played Jota in to make it 2-0 just seconds into the second half.
At 2-0, it meant Wolves' task became virtually impossible even though they went 2-0 up, they let it slip back to 2-1 before going on to win 4-2.
The Bees were in dreamland as Rudy Gestede fired home to give Blackburn a 3-1 lead against Ipswich.
Michael Hector made it 2-0 to Reading to spark jubilant scenes at Griffin Park before Andre Gray wrapped up the points for the Bees, making Wolves' plight irrelevant as far as Brentford were concerned.
Ipswich pulled a goal back through Murphy's penalty but their defeat was enough to drop below Brentford into sixth.
But it was Derby who dropped out on the play-offs as Gareth McCleary converted a penalty five minutes from time to ensure a comfortable win for the Royals on a day the Royal Family welcomed a new member.
The final whistle was greeted by a joyous pitch invasion and Brentford will face Middlesbrough in the semi finals with a chance to progress to Wembley and play for a place in the Premier League.