The forward struck the decisive goal in the 75th minute, emphatically converting Habib Diarra’s low cross to seal a 1-0 victory over Fulham at the Stadium of Light.
The goal capped a memorable week for Isidor, who celebrated his birthday and signed a new contract with Sunderland.
“I’m really happy,” he told club website.
“I missed the first chance that came my way, but I had to reset and scored the second.
“I have to thank Habib Diarra for setting me up. He put a great ball across and I was there to finish it."
Isidor netted six Premier League goals last season and already has one to his name this time around, with the Haiti international expected to take up an important role as Sunderland enter the Europa League later this month.
“Every time the fans sing my name, it is an amazing feeling,” he added.
“Thank you so much for supporting me like that.”