[4] He was a candidate for the Democratic nomination for lieutenant governor of Pennsylvania in 2022, finishing in second place behind Austin Davis with 25% of the vote.

[12] Sims worked as the president of Equality Pennsylvania and the chairman of the Gay and Lesbian Lawyers of Philadelphia (GALLOP), until he stepped down from both positions in 2011.

In 2009, Sims joined the faculty of the Center for Progressive Leadership and the National Campaign Board of the Gay & Lesbian Victory Fund.

[13] Before assuming public office, Sims served as staff counsel for policy and planning at the Philadelphia Bar Association.

[14] During his time at the Bar Association, Sims worked with attorneys, legislators and community organizations on issues ranging from gender and pay inequity to environmental regulation.

"[20] Sims made national news on October 3, 2013, when he and fellow Democratic Rep. Steve McCarter introduced legislation to legalize same-sex marriage in Pennsylvania.

[21] Sims has also introduced a bill with fellow Democratic State Representative Erin Molchany to help reduce and eliminate the gender gap in rate of pay as well as legislation to ban the practice of conversion therapy with Rep. Gerald Mullery.

[30] Sims served on the House Commerce, Game and Fish, Human Services, State Government, and Tourism and Recreation Committees.

[32][33][34][35] Sims received attention in 2019 for videos he posted to social media confronting people protesting outside of a Planned Parenthood facility in Philadelphia.

[38][36][37] Facebook removed the video, in which he was "yelling pretty aggressively" at the three girls, aged 13 to 15, for violating their community standards around "coordinating harm.

[37] A few weeks later, in May, Sims posted another eight-minute video of himself confronting a woman who was quietly praying with a rosary outside the same facility.

Following his loss, Sims was involved in a car crash with a state owned vehicle, injuring two people.

[47] In December 2022, Sims became the Managing Director of Government Affairs and Public Policy at Out Leadership in New York City.