After five seasons in North Carolina, she was traded to the Kansas City Current and then flipped to NJ/NY Gotham FC, where she won her fourth championship in 2023.

Born in Fresno, California to Christine and David Williams, Lynn attended Bullard High School where she played on the varsity team and earned all-league and all-area honors all four years.

[2] She was a finalist for the Hermann Trophy, was named first-team All-American by the NSCAA and Soccer America as well as All-WCC first team for the third straight year.

In the NWSL Playoffs Williams scored two goals in extra time as the Flash upset the Portland Thorns in the semi-final and advanced to the Championship Game.

[14] She played every minute of North Carolina's playoff games in 2018 as the Courage won the 2018 NWSL Championship by defeating the Portland Thorns 3–0 in the final.

[15] In October 2019, Williams travelled to Australia to join W-League club Western Sydney Wanderers on loan.

[17] In December 2021, Williams returned to Australia, signing with Melbourne Victory as a guest player on a month-long loan.

[20] On Monday January 10, Williams was traded to the Kansas City Current from the North Carolina Courage for $200,000 in allocation money, the rights to goalkeeper Katelyn Rowland and a 1st round pick in the 2023 NWSL Draft.

Williams was injured on March 18, 2022, suffering a right leg injury, missing the entirety of the 2022 NWSL season.

[23] She opened scoring against OL Reign in the championship game to help her team win 2–1, becoming the league's first four-time champion.

[24] Williams scored her 79th NWSL goal on May 19, 2024, heading in the ball against the Chicago Red Stars, to pass Sam Kerr as the league's all-time leading scorer.

[26] After a breakout 2016 NWSL season Williams received her first call-up to the United States women's national team in October 2016 for a pair of friendlies against Switzerland.

[33] In late 2019, after incoming head coach Vlatko Andonovski took over for a retiring Jill Ellis, Williams was again called up to the national team.

In her first five games back with the team, including the CONCACAF Olympic qualifying tournament, Williams tallied five goals and five assists.

[34] On July 12, 2024, it was announced that Williams would replace Catarina Macario on the roster for the 2024 Summer Olympics after initially being named an alternate.

In USA's 2nd game of the Olympics, facing Germany, Williams was subbed on in the 2nd half where she scored the teams 4th goal of their 4-1 victory.

[35][36][37] She appeared as a substitute in the gold medal game against Brazil, which the United States won 1–0 on a goal from Mallory Swanson.