In 2012, Rinaldi placed third in the Republican primary election for the House District 115 seat. On March 4, 2014 the one-term incumbent, Bennett Ratliff, narrowly lost re-nomination to Rinaldi, who received 4,167 votes to Ratliff's 4,075 votes. Rinaldi's 2014 campaign received support from the Tea Party movement, Texans for Fiscal Responsibility, Texas Eagle Forum and Texas Right to Life, among others. In the Republican primary held on March 1, 2016, incumbent Rinaldi held off the challenge from Ratliff who tried unsuccessfully to regain his seat. The voters favored Rinaldi, 8,804 to 7,668. Rinaldi narrowly held on to his House seat in the general election held on November 8, 2016. He polled 29,987 votes to 28,939 for the Democrat Dorotha M. Ocker.
84th legislative session
During the 84th legislative session, Rinaldi served on the Agriculture & Livestock committee and the Business & Industry committee. He joint- and co-authored successful pieces of legislation that were signed into law, including: HB 11, and HB 283. Rinaldi fought to eliminate or minimize the effects of the Robin Hood plan on Texas public school districts with HB 945 and HB 1411. Rinaldi co-authored legislation that would repeal in-state tuition and end welfare benefits for undocumented immigrants as well as penalize businesses that knowingly hire undocumented immigrants. Rinaldi was rated the number one conservative in the Texas House by a Rice University study that drew on the 1,138 non-lopsided roll call votes taken during the 2015 regular session. He received a 100 percent rating which tied him in the number one spot on the Texans for Fiscal Responsibility index with seven other conservative members. He was also the top-rated Representative by the Texas Eagle Forum with a 98% rating. Rinaldi had a 100 percent record on the Texas Right to Life scorecard and was designated by the organization as one of 14 "Pro-life Heroes" in the legislature for his work in passing pro-life legislation.
85th legislative session
During the 85th legislative session, Rinaldi served on the Agriculture & Livestock committee and the Judiciary & Civil Jurisprudence committee. Rinaldi was, according to the Dallas Morning News, "instrumental in strengthening the punishments in the sanctuary cities ban," and authored and passed into law measures that: remove from office public officials who adopt sanctuary city policies, require government contractors and subcontractors to use e-verify, revoke pensions of teachers convicted of committing sex crimes against students, allow churches to utilize volunteers to provide security services without risking heavy fines, and prohibit any taxpayer money from going to Planned Parenthood. He also re-introduced legislation he had previously proposed to end the Robin Hood school finance system. He served as the Pro-Life Whip for Texas Right to Life. Rinaldi also co-founded the Texas Freedom Caucus during the 85th legislative session. The caucus was founded by members of the House of Representatives committed to protecting life, strengthening family values, defending the Texas and U.S. Bill of Rights, restraining government and revitalizing personal and economic freedoms. In May 2017, Rinaldi called Immigrations and Customs Enforcement officers on protesters inside the Capitol building. Rinaldi claimed that he called ICE after seeing individuals holding protest signs indicating they were illegal immigrants. An altercation ensued; according to multiple Hispanic Democratic lawmakers, Rinaldi got into their faces during the dispute and cursed at them. Video shot from the House floor showed both Republicans and Democrats pushing each other. Rinaldi claimed that Representative Poncho Nevárez threatened his life during the incident, which Nevárez denied. Democratic lawmaker Justin Rodriguez claimed that Rinaldi threatened to "put a bullet in one of my colleagues’ heads"; Rinaldi did not deny making the statement, but claimed it was made in self defense. Rinaldi’s actions were widely seen as having a racial motivation. After the incident, state representative Ramon Romero Jr. said Rinaldi had "racially profiled every single person that was in the gallery today." During Rinaldi's second term, he remained ranked as the most conservative legislator in Austin according to a Rice University's study roll-call vote analysis drawing on 1,460 non-lopsided roll-call votes taken during the 2017 regular session. He was also named one of the Top 10 Legislators by Empower Texans, as well as one of the Top 10 Worst Legislators by Texas Monthly. His voting record earned a 100 score from Texans for Fiscal Responsibility.
86th legislative session campaign
Rinaldi lost his state House seat in 2018 in the Democratic tide that swept Dallas County. Rinaldi was unseated by Democrat Julie Johnson, whose campaign included volunteers that Rinaldi had called ICE on in May 2017 at the Texas Capitol. Receiving 24,512 votes versus Johnson's 32,214 votes, Rinaldi received the lowest vote percentage of any House incumbent in Dallas County.
