Born in Hendersonville, Tennessee, Newgarden drove a kart for the first time at the age of thirteen. In 2006, he took titles in two classes of the Kart Racers of America – Junior Yamaha championship and won the Junior TAG World Championship.
Newgarden started his single-seaters career in the Skip Barber Racing School series in 2006. He finished as runner-up in the Southern Regional Series with three wins and another seven podium places. He next competed in the 2007 BFGoodrich / Skip Barber National Presented by Mazda championship, finishing sixth with two wins. Newgarden remained in the series for 2008 and improved to second place, with three wins.
After some participations in Formula Ford races in 2008 and a win in the Kent Class at the Formula Ford Festival, he moved to the British Formula Ford Championship in 2009. Again he was runner-up, amassing 550 points and nine wins.
Formula Palmer Audi
Newgarden competed in the opening round of the 2009 Formula Palmer Audi season at Brands Hatch, taking two wins and a fourth in the third race.
Newgarden move into the new-for-2010 GP3 Series with the Carlin team. He finished 18th in points, with a pole position at Hockenheimring and a best finish of fifth in the season finale at Monza.
Josef Newgarden clinching the Indy Lights Championship
In 2011 Newgarden returned to North America to race in the Indy Lights series for Sam Schmidt Motorsports. He won his first Indy Lights race in the season opener on the Streets of St. Petersburg. He followed his opening win in St. Petersburg with four more wins and ten podium finishes out of thirteen races in 2011, clinching him the points championship with one race to go. In New Hampshire, the 11th race of 2011, Newgarden lapped the entire field and went on to win. He was the first Indy Lights driver to do this since Thiago Medeiros in March 2004.
2012–2014: Sarah Fisher Hartman Racing
On December 7, 2011, Newgarden was announced as the driver for Sarah Fisher Hartman Racing. He competed in IndyCar from 2012 to 2014 with Sarah Fisher's team, earning his first podium at the 2013 race in Baltimore. He narrowly missed the win at the 2014 Iowa Corn Indy 300 due to problems with his last pit stop.
2015: CFH Racing
During his fourth full season in IndyCar, Newgarden raced under the merged team of Sarah Fisher and Ed Carpenter. Under this new team banner, Newgarden started 2015 strong, finishing in 12th position at St. Petersburg and improving his position with each race.
During the fourth race weekend in the 2015 season, he earned his first Indycar Series victory at the 2015 Honda Indy Grand Prix of Alabama, moving from 5th to 2nd on the first lap of the race, and leading the most laps on the way to a 2.2-second win.
He won again later in the season at the 2015 Honda Indy Toronto and finished the 2015 season 7th in the standings with 431 points, a personal best in IndyCar.
2016: Ed Carpenter Racing
Sarah Fisher ended her participation in IndyCar after the 2015 season, leaving Newgarden to drive for the reformed Ed Carpenter Racing.
Newgarden started the 2016 season strong with a podium at the 2016 Honda Indy Grand Prix of Alabama at Barber Motorsports Park. He barely missed pole position during qualifying for the 2016 Indy 500 and started in the middle of the front row. He finished the 100th running of the Indy 500 in a strong 3rd.
At the 2016 Firestone 600 at Texas Motor Speedway Newgarden crashed hard into the wall, breaking both his hand and clavicle. Remarkably, he returned to the car two weeks later, working his way to a top 10 spot at the 2016 Kohler Grand Prix at Road America.
Only 28 days after his crash at Texas, Newgarden won the 2016 Iowa Corn 300. He led 282 of 300 laps in the race, "destroying" the field. A remarkable achievement with a broken hand and shoulder.
At IndyCar's return to Watkins Glen International, the 2016 Grand Prix at the Glen, Newgarden claimed another podium, finishing 2nd. After a 6th place finish at the 2016 GoPro Grand Prix of Sonoma, he finished the season in 4th place overall in the season standings.
2017–present: Team Penske
On September 29, 2016, ECR owner Ed Carpenter confirmed that Newgarden would not be back with the team in 2017. Newgarden moved to Team Penske for the 2017 season, with the team making an official announcement on October 5.
Newgarden won his first race with Team Penske during round 3 of the 2017 season at Barber Motorsports Park; clinching the victory after a duel with Scott Dixon in the final laps. Newgarden moved into the IndyCar points lead following back to back victories at Toronto and Mid Ohio.
At Gateway, Newgarden held off his teammates and Scott Dixon to clinch his fourth series victory of the season, but not without controversy, as late in the race Newgarden went under teammate Simon Pagenaud very late going into Turn 1. After bumping tires both continued, but, as Pagenaud nearly hit the wall, he was not pleased with his teammate's move. The following week at Watkins Glen, Newgarden had a sizable cushion in the points over second place Dixon. Coming back onto the track after a pit stop under green on cold tires, he lost control of the car and Sebastien Bourdais made contact with him damaging the suspension. Newgarden ended up leaving the Glen with a three-point lead, later a four-point lead as he won the pole for Sonoma, setting a track record. Newgarden needed to finish 4th or higher regardless of Pagenaud's result and he finished 2nd to clinch his first title. Newgarden became the first American born driver to win the Astor Cup since Ryan Hunter-Reay in 2012.