The striker's commitment to Old Trafford had been questioned and he was left out of key games last season under Alex Ferguson, who also took to playing him in more of a midfield role as Robin van Persie took the goalscoring glory.
Rooney is fourth on United's all-time leading scorers' list, behind Bobby Charlton (249), Denis Law (237) and Jack Rowley (211) and his manager can see him going further.
"I remember coming in and saying you've got a real chance to be one of the all-time leading goalscorers at this club and I tell you what if he keeps playing like he did tonight he will get there," Moyes said.
Along with the rousing reception Rooney has been getting from the Old Trafford crowd, despite a turbulent few months, Moyes' faith in him seems to have lifted the England striker's mood and his game.
Ferguson had said in May that Rooney wanted to leave the club, triggering a close season of speculation over his future and an ultimately unsuccessful but very public pursuit by Chelsea and Jose Mourinho for his signature.
As the rumours swirled, Rooney himself never spoke publicly on the matter and on Tuesday when asked about it he was still keen to avoid the issue of whether he wanted to stay or go.
"Listen, I will concentrate on my football as I have done all summer," he told ITV after a 4-2 victory over Leverkusen in their Champions League opener. "I got my head down in the summer, worked hard and I'm concentrating on my football.
"The fans here have been fantastic with me and the reception I get here is great. Hopefully I can reward them with goals and performances like tonight."
Moyes had long said Rooney was training well and was in a good frame of mind and slowly but surely he has been proven right as the striker - deployed in his more traditional role - has enjoyed a good start to the season.
Having been United's best player in last month's 0-0 draw with Chelsea in the Premier League and having scored from a free-kick in Saturday's 2-0 win over Crystal Palace, Rooney took his performance to a new level against Leverkusen.
He volleyed in a 22nd-minute opener, netted the third with a right-footed shot to bring up 200 for United and then passed superbly to assist the fourth scored by Antonio Valencia.
His goals have come since he started wearing a headband to protect his forehead after suffering a deep gash and, whether that is a lucky charm or a mere coincidence, Rooney is delighted to have reached another milestone.
"It's something I'm very proud of, I'm pleased to score 200 goals for a club like Manchester United and hopefully there is more to come," he said.
"I'm delighted to be back playing and scoring and this was a good result. The first game in the Champions League is always important and thankfully we got the victory."
It has taken Rooney 406 appearances to notch his double century, meaning he averages nearly a goal every other game, and being still only 27 years old, he has time to overtake Charlton.
"It (the record) was something we made him aware of," Moyes said. "More importantly, I wanted to get him back in a good condition and mentally correct when he was ready to play.
"I think you see (that), he is moving as well as he has done, he's in a good place himself at the moment, any centre forward who is scoring goals feels good about himself."
Rooney's latest goals took him to second in United's Champions League scorers chart, past Ryan Giggs. He now has 30 goals, eight shy of Ruud van Nistelrooy's record tally.
Leverkusen manager Sami Hyypia could only watch in awe as Rooney tore his side apart.
"He showed he can score a lot of goals," said the former Liverpool defender, who knows from his playing days how hard it is to come up against Rooney.
"He still has a few years left, to score 200 goals is a good achievement... it looks so easy how he is playing, he showed today he is a quality player."
- Sports & Recreation