Spurs take on the Bees at Tottenham Hotspur Stadium after overcoming Stoke City in the last eight almost a fortnight ago.
The club is now just two wins away from a first major trophy since it won the same competition in 2008, beating Chelsea 2-1 through Jonathan Woodgate's extra-time goal.
Mourinho has won the Carabao Cup four times – three with Chelsea and one with Manchester United – and is looking to become just the third manager to reach the final with three different clubs after Ron Atkinson (United, Sheffield Wednesday and Aston Villa) and Ron Saunders (Norwich City, Manchester City and Villa).
But he will have his work cut out against a Brentford side who have already eliminated four Premier League teams in this season's competition in Southampton, West Brom, Fulham and Newcastle United.
Indeed, the Bees are only the second non-Premier League side to achieve that feat in a season after Bristol City in 2017-18.
Mourinho, who has won 15 of his 17 home EFL Cup and FA Cup matches as against teams from outside the top flight, knows only too well the confidence boost a trophy triumph would bring and is determined to end Spurs' drought.
Asked at a media conference if it was the biggest game since he took over at Spurs in November 2019, Mourinho said: "I think so, in the perspective that the club has been chasing silverware for many years.
"We had a match at Crystal Palace [last season] which gave us participation in the Europa League and that match was important. The only thing more important is finals.
"For me, every competition is important. I won the EFL Cup in my first season [in England in 2004-05], so for me, every competition is important; it doesn't matter where you are or what your ambitions are.
"Especially for a club without silverware for more than a decade. If we win two matches, we win the trophy, which would be a very good thing for the club and players.
"It is not about me winning it five times with two or three clubs. It's about the players that want trophies and fans that want trophies. We just need two victories.
"We have to look to this semi-final with this ambition and respect a very good team."
Mourinho confirmed Erik Lamela would not feature against Brentford but did not reveal if his absence was due to his breach of coronavirus regulations.
Pictures circulated on social media of Lamela alongside Spurs team-mates Sergio Reguilon and Giovani Lo Celso at a festive gathering, with West Ham's Manuel Lanzini also in attendance.
The party went against COVID-19 rules put in place by the UK government as those present ignored social-distancing guidelines.
Spurs players Sergio Reguilon, Giovani Lo Celso, Erik Lamela and West Ham's Manuel Lanzini were all pictured breaking lockdown rules over the Xmas period.— Footy Accumulators (@FootyAccums) January 2, 2021
Duncan Castles is now reporting that both Erik Lamela and Giovani Lo Celso have tested positive for COVID. pic.twitter.com/YvZBD8WkQA
Reguilon was an unused substitute for Spurs' 3-0 Premier League win over Leeds United on Saturday, but there was no place in the squad for Lamela. Lo Celso remains out injured.
Asked if Lamela would be available, Mourinho said: "Not for me to tell you. Just to tell you that against Brentford he cannot play."