A "league championship" refers to the ultimate victory or title awarded to the best team in a specific sports league. This team has outperformed all the other teams in the league and has become the overall champion. Full definition
In the game you become a manager of a soccer team, who competes in league championships in one of 50 available countries. (gamepressure.com)
Playing for a state title is a long way from earning the program's first playoff bid in 2011 and winning the first league championship in 2014. (sportstarsmag.com)
On the other hand, improving insulin sensitivity is like a home run in a major league championship series. (resistantstarchresearch.com)