The Sunderland man, on loan with the Tigers, converted Elmohamady's ninth-minute rightwing cross to give his side the lead at the Liberty Stadium before Chico Flores replied for the home side on the hour-mark.
After the match, Egypt international Elmohamady was pleased for Graham who helped Hull remain 12th on the Premier League table.
"First, I have to congratulate him as it's been a long time for him. He works very, very hard in the games and in training as well," he told Sky Sports.
"He's on the scoresheet again and it's very good for him, and very important for the team."
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