The contract announced by the MLS expansion side Wednesday runs through 2025 with an option for 2026.
Swiderski, 25, will occupy an international roster slot on Charlotte's inaugural roster in 2022.
Swiderski joins Charlotte on a permanent transfer from the Greek club PAOK FC, where he tallied 35 goals and 14 assists in 135 matches from 2018-22. He helped the team win three trophies: the 2018-19 Super League Greece and two Greek Cups.
"We're delighted to welcome a player of Karol's caliber to Charlotte FC to spearhead our attack. He's proven to be a lethal goal scorer at both the club and international level, and to secure his signing as our first Designated Player is an excellent achievement for our Club," Charlotte sporting director Zoran Krneta said in a news release.
"Karol's profile as a striker is everything we need in a number nine and he is a player who is entering the prime of his career. His performances for Poland on the international stage speak for themselves and we're confident Karol will be one of the toughest strikers to defend in the league. Additionally, he has a high work ethic, a title-winning mentality, and will bring excellent leadership and character into the locker room."
Internationally, Swiderski debuted with Poland's national team in March 2021. He scored five goals in nine matches in the 2022 FIFA World Cup qualifying cycle.