Mousinho, 31, has captained the Brewers in all three Football League divisions, but had not played in the second tier before last season.
"The Championship was a bit of an unknown for me," he told Burton's official website.
"Now I feel in a better place with that season under my belt."
Mousinho made 32 appearances in the Championship in 2016-17, starting in Burton's victories over Sheffield Wednesday, Norwich, Huddersfield and Leeds, all sides who finished in the top eight.
And while he admits the Brewers will no longer carry the element of surprise, Mousinho says the team, who were playing non-league football less than a decade ago, will be stronger following their maiden campaign at Championship level.
"Maybe a few underestimated us last season and I don't think that will happen again," he added.
"It will be a completely different challenge but we have more experience, we know what it takes, what the level is all about and as last season went on we got better and better.
"Next season I think we will be set up well but there will be new challenges and we will relish that."
Burton Albion skipper John Mousinho says he is relishing a second season in the Championship after signing a new one-year contract.