After a goalless first-half, Shelvey, who had requested to play for the Magpies' second string at Motspur Park, headed home from close range following Tom Allan's inviting cross to maintain the youngsters' push for promotion in Premier League 2.
United's fourth league win in a row kept United in fourth place on 31 points, five points adrift of Division Two leaders Southampton.
"Tonight was a professional performance," Dawson told nufc.co.uk. "We weren't at our best in the first half yet we still controlled large periods of the game and created some chances, especially from set plays.
"We tried to fix a couple of things at half-time and the players responded by playing at a much better intensity, making better decisions in possession which led to our goal.
"It was important that we focused on being more hard to beat, knowing that if we kept a clean sheet it would give us something to hang on to. After that, we always know that people like Tom, Yannick (Touré), Rosaire (Longelo) and obviously Jonjo will create some opportunities coupled with our increased threat from set pieces.
"A clean sheet is very pleasing too. Everyone contributed to making it a comfortable night for Nathan (Harker). They worked well both individually and as a team to press and restrict spaces for Fulham's attackers."
Shelvey showcased his experience at first-team level in playing a major part for United's decisive goal, beginning the attacking move with a trademark diagonal pass before eventually nodding home inside the penalty area.
The inclusion of the central midfielder for Newcastle's second string proved beneficial for Dawson's side, with the coach believing that Shelvey's 62-minute appearance would be useful for the developing youngsters.
"Jonjo slotted in well to the team and gave an assured performance," he said. "He pressed well out of possession and triggered a lot of good things that we did on the evening.
"The goal was a well worked team goal with a pinpoint cross from Tom Allan. It was great for Jonjo to get on the end of the move that he started but I'm even more pleased with the way the team applied some of the principles that we have worked on recently.
"Whenever we get first team players asking to play for our team, the players respond positively. They understand the benefits of having someone of Jonjo's experience with us and grasp the opportunity to learn from him."
Photograph courtesy of Fulham FC
