And the former Arsenal trainee did it in style, setting the Robins on their way to a vital 3-2 victory at fellow League One strugglers Shrewsbury.
Emmanuel-Thomas had gone 12 games without scoring until blasting City in front at Greenhous Meadow with an unstoppable strike.
Cotterill now hopes his 19-goal top scorer can kick on and weigh in with more goals to lift the Robins to safety.
"It's a big relief for him," said Cotterill. "He's gone a few games without a goal and after scoring as many goals as he did so early on in the season everybody thinks all of a sudden he's going to get 30 goals.
"There aren't many people who get to 30 goals but hopefully he's had his lean spell and now he can score a few between now and the end of the season."
Cotterill was delighted to see City emerge with maximum points after a contest in which fortunes for both sides ebbed and flowed.
Tamika Mkandawire cancelled out the City opener with a fine strike from 30 yards just before the break but then scored an unfortunate own goal to restore the visitors' lead early in the second half.
Paul Parry headed Shrewsbury level for a second time before Joe Bryan nodded in a 63rd-minute winner for Cotterill's men to lift them three points clear of the bottom four.
"It was always going to be a tough game, we knew that," said Cotterill. "It was fantastic to get the three goals. We were delighted with that.
"We were probably always going to concede because we were always looking to score. I'm sure it was entertaining if there were any neutrals here."