The midfielder played under Powell at Huddersfield and the pair are set to work together again at Derby.
Derby County's Jacob Butterfield says he's excited to be working with Chris Powell
Butterfield says the club have made the right managerial calls this summer
Powell, who previously managed Charlton Athletic before his time in West Yorkshire, was brought to the iPro shortly after Pearson was appointed at the end of May, with County looking to plot another push for promotion.
Having missed out on going up via the play-offs last season, Derby will be hoping to make a real mark on the Championship this year, and Butterfield believes they have the managerial expertise to move forward next term.
Butterfield worked with Powell at Huddersfield
But while full of praise for boss Pearson, it is the chance to work with his former manager that has left Butterfield really excited.
He told the Derby Telegraph: "He's [Powell] a good guy and a good coach, so I am sure that he will be brilliant around the place.
Powell has been appointed assistant manager at the iPro
"He was very laid back as a manager, trusted his players and created a good atmosphere. People enjoyed playing under him and I am sure he will have an effect here as a number two."
The former Middlesbrough ace showed some promising form during his time under Powell, netting seven goal in 52 appearances, before completing a £4 million move to Derby last summer.
The 26-year-old has since gone on to play 40 games for the Rams and has scored eight goals.