Selemani Mwalimu netted from the penalty spot in added time after two sides could not be separated after 90 minutes.
Barker only joined the Tanzanian giants in December after parting ways with Stellenbosch and this success comes after two Coach of the Month accolades and his side in second place on the Tanzanian Premier League standings.
This was Simba's first win over league leaders Yanga in eight games and in reaching the final, they beat Mlandege FC 3-0, as Yanga saw off Azam FC 2-1.
Barker previously led Stelles to victory in the Carling Knockout Cup in 2024.
