The 62-year-old Dutchman has led the Red Devils to three successive pre-season victories after signing a three-year deal at the 20-time English champions in May.
United finished in a disappointing seventh place last season as Sir Alex Ferguson’s successor Moyes was sacked with four Premier League games remaining in the campaign.
And United’s all-time record goal-scorer Charlton is confident that his former club will thrive under a “really clever man”.
“It’s marvellous. I am so pleased with the way it has turned out,” Charlton told MUTV.
“We struggled a little bit last year and maybe a few people made a few mistakes but I don’t think we will make them now.
“Hopefully we will be well-served by a really clever man.”
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news