Representative Andy Kim was elected on Tuesday to the U.S. Senate by a decisive margin, according to The Associated Press, after a tumultuous campaign that grew out of a corruption scandal that engulfed New Jersey’s former senator, Robert Menendez, a once-powerful Democrat.

Mr. Kim’s campaign was defined by his ability to vanquish New Jersey’s first lady, Tammy Murphy, and topple a longstanding source of electoral power for the state’s Democratic and Republican political machines.

A son of immigrants, Mr. Kim, 42, a Democrat, will become the first Korean American in the Senate and its third-youngest member when he takes the oath of office.

Mr. Kim is expected to be sworn in later this month, in an arrangement laid out by the governor when Mr. Menendez resigned after being convicted of peddling his political influence for bribes of gold bars, $480,000 in cash and a Mercedes-Benz convertible.

“We showed that politics isn’t some exclusive club, just for the well-off and the well-connected,” Mr. Kim told supporters gathered in Cherry Hill, N.J., to celebrate his victory.

“I believe that the opposite of democracy is apathy, and, by extension, I hope that you see our campaign as a means of being the opposite of that helplessness,” he added.