Vidak was born in Visalia, California to James Vidak, the Tulare County superintendent of schools, and Kathleen Vidak. The eldest of five children, he graduated from Redwood High School in 1984 and then attended College of the Sequoias in Visalia and California State University, Fresno before receiving his Bachelor of Science degree in Animal Business from Texas Tech University. He returned to the San Joaquin Valley to work in the produce industry before opening his own cherry farm outside Hanford in 1997.
In the 2010 midterm elections, Vidak announced his intention to run for Congress in California's 20th congressional district, challenging longtime incumbent Democrat Jim Costa. The race was too close to call on election night and was only settled three weeks after Election Day. Costa ultimately won reelection with 52% of the vote against Vidak's 48%, with a total popular vote margin of 3,050, in the closest race of Costa's Congressional career up to that point.
Following the sudden resignation of incumbent Democrat Michael Rubio on February 22, 2013, the 16th State Senate seat was left vacant and a special election was called.
Vidak's main challenger in the election was Leticia Perez, a former criminal defense attorney and supervisor of Kern County's 5th district. In the May 21 primary election, Vidak appeared to win outright with over 52% of the vote, but enough late absentee and provisional ballots counted in the next few days favored Perez and pushed Vidak down to 50%, sending the race to a general election on July 23 between him and Perez. In the general election, Vidak defeated Perez with 52% of the vote compared to Perez's 48%. The popular vote margin between the two was 3,084, just barely higher than the same margin by which Vidak lost to Jim Costa three years earlier.
Vidak's win marked the first time since 1996 in which the winning state Senate candidate of a special election was not from the same party as the incumbent. It is also marked the first time that a Republican took a Democratic State Senate seat since 1993, and the 8th time overall (in regards to special elections). It was also the first time in 18 years that the 16th district has seen a Republican State Senator, since Phil Wyman represented the district briefly during 1993–95. (Then assemblyman Costa beat Wyman in 1994 and served until being termed out in 2002. He was succeeded by Democratic assemblyman Dean Florez who served from 2002 to 2010).
Vidak ran for reelection, for his first full term, in November 2014. By the time of the primary, the 16th district was redrawn into the 14th district. His sole Democratic challenger was Luis Chavez from Fresno. In the June 3 primary, Vidak came in first with 61% of the vote ahead of Chavez. In the November 4 general election, Vidak defeated Chavez by a smaller margin of 54% to Chavez's 46%.
Vidak was sworn-in on August 10, 2013.
On September 11, 2013, Vidak asked for the Senate to vote on whether or not the people of California should be allowed to revote on the High-Speed Rail project due to a sharp increase in prices and costs of the project. The effort failed due to 24 Democrats voting against it, while 11 Republicans voted in favor. Vidak has continued his efforts to delay, defund, or hold a revote on the project throughout his time in the Senate.
On October 16, 2013, Vidak joined fellow Senator Anthony Cannella of the 12th district in calling for an investigation into the California Employment Development Department after it ceased providing unemployment benefits to over 150,000 Californians and closed several offices in Turlock and Los Banos.
In response to Governor Jerry Brown's declaration of a state of drought for California, Vidak joined with Senator Cannella once again to pass legislation geared towards storage and protection of water throughout the state. On January 30, 2014, they announced the result as Senate Bill 927, which would put a water bond on the November 2014 ballot that would include efforts to store and protect clean water and clean already-contaminated water, at a cost of $9.2 billion. Vidak also wrote a letter to President Barack Obama asking for support, and was interviewed by Lou Dobbs on the Fox Business Network to further explain the crisis, its causes, and ways to solve it.
In June 2014, Vidak was one of five State Senators who was awarded a perfect score by the California Chamber of Commerce for voting against Senate bills that were identified as "job-killers."
In October 2014, Vidak was named the "Most Fascinating Person of 2014" by the Center for the Blind and Visually Impaired (CBVI) and the Advanced Center for Eyecare (ACE). He was also named "Legislator of the Year" by the California Small Business Association (CSBA) and the California Small Business Roundtable (CSBR).
In March 2016, Vidak introduced Senate Bill 976, which sought to extend the one-year ban on lobbying by ex-lawmakers to two years, and possibly up to four years, in an effort to curtail the revolving door effect. Later that same month, Vidak was credited with saving a woman's life by directing traffic away from a Sycamore tree with a breaking branch about half a mile from the Capitol, after he could hear the sound of the wood cracking. Due to his intervention, driver Tracy Courtney stopped her car just as the branch broke, crushing the front end of the car but narrowly missing her. Vidak credited the incident to Divine Intervention, saying: "I walked that direction for a reason I guess. God put me on that path and in that direction and I heard it."
In July 2017, Vidak spoke out against AB 398, an extension of the state’s efforts to combat climate change known as "cap-and-trade,” which included such measures as tax hikes. In his speech on the floor of the State Senate, Vidak said “I represent the poorest district in the state. I cannot, in good conscience, vote for yet another bill that will raise gasoline and electricity rates on the poorest of the poor.” His speech received praise from Breitbart, which called Vidak’s speech the most “eloquent” of all the Republicans who spoke out against the bill. The bill ultimately passed through the legislature with the support of seven Republicans in the Assembly, including the Republican Assembly leader Chad Mayes, and one Republican State Senator, Tom Berryhill.