Rubin turned pro in June 2015 at the age of 19.
He made his first final on the ATP Challenger Tour at Charlottesville, and won by defeating fellow American teenager Tommy Paul, despite being down 5–1 in the second set with Paul serving for the match.
As the only American to win an event in the Australian Open Wild Card Challenge, Rubin was awarded a wild card into the main draw at the Australian Open.
With his wild card, Rubin entered his second career Grand Slam event as the lowest-ranked non-PR player (328th overall) in the main draw of the 2016 Australian Open, where he beat the 17th-seeded Benoit Paire in three tiebreaks in the first round.

Rubin cracked the Top 200 for the first time by qualifying for the 2016 Indian Wells Masters tournament.
In the clay court season, he recorded an upset win over 59th-ranked Denis Kudla, the No.
1 seed at the Sarasota Open.
Having missed most of the summer tournaments due to a rolled ankle injury he suffered while jogging in June that cost him five months of training and competition, Rubin returned to form in October, reaching his second career Challenger final at Stockton.

Rubin started the 2017 season by winning his first round match at the Australian Open, before falling to eventual champion Roger Federer in the second round.
He then went back to Australia and won his second Challenger title at Launceston, Tasmania, in an all-American final against Mitchell Krueger.
For the second consecutive year, Rubin missed a few consecutive months of the late spring and early summer due to injury; this one a severely sprained right wrist that he suffered in April when he slipped on a clay court during a tournament in Houston that resulted in him losing 10 months of serious competition and training.
He bounced back near the end of the season to finish the year on the cusp of the Top 200, just as in 2016.

Once again, Rubin began the 2018 season by playing at the BNP Paribas de Nouvelle-Calédonie.
At this tournament, he greatly improved on his second-round result from last year and reached his fourth Challenger final, all four of which have been against other Americans.
In the final, Rubin defeated Taylor Fritz to claim his third Challenger title to boost himself to a new career-high ranking of No.
162 in the world.
After falling out of the Top 200, Rubin won a fourth Challenger title at the Tallahassee Tennis Challenger.
This was his first title on clay and put him back in the Top 200 of the ATP rankings.
The title also helped him clinch the French Open Wild Card Challenge to earn a wild card into the main draw of the French Open.
In his debut at the tournament, he was beaten by compatriot John Isner.
Rubin turned pro in June 2015 at the age of 19. He made his first final on the ATP Challenger Tour at Charlottesville, and won by defeating fellow American teenager Tommy Paul, despite being down 5–1 in the second set with Paul serving for the match. As the only American to win an event in the Australian Open Wild Card Challenge, Rubin was awarded a wild card into the main draw at the Australian Open. With his wild card, Rubin entered his second career Grand Slam event as the lowest-ranked non-PR player (328th overall) in the main draw of the 2016 Australian Open, where he beat the 17th-seeded Benoit Paire in three tiebreaks in the first round.
Rubin cracked the Top 200 for the first time by qualifying for the 2016 Indian Wells Masters tournament. In the clay court season, he recorded an upset win over 59th-ranked Denis Kudla, the No. 1 seed at the Sarasota Open. Having missed most of the summer tournaments due to a rolled ankle injury he suffered while jogging in June that cost him five months of training and competition, Rubin returned to form in October, reaching his second career Challenger final at Stockton.
Rubin started the 2017 season by winning his first round match at the Australian Open, before falling to eventual champion Roger Federer in the second round. He then went back to Australia and won his second Challenger title at Launceston, Tasmania, in an all-American final against Mitchell Krueger. For the second consecutive year, Rubin missed a few consecutive months of the late spring and early summer due to injury; this one a severely sprained right wrist that he suffered in April when he slipped on a clay court during a tournament in Houston that resulted in him losing 10 months of serious competition and training. He bounced back near the end of the season to finish the year on the cusp of the Top 200, just as in 2016.
Once again, Rubin began the 2018 season by playing at the BNP Paribas de Nouvelle-Calédonie. At this tournament, he greatly improved on his second-round result from last year and reached his fourth Challenger final, all four of which have been against other Americans. In the final, Rubin defeated Taylor Fritz to claim his third Challenger title to boost himself to a new career-high ranking of No. 162 in the world. After falling out of the Top 200, Rubin won a fourth Challenger title at the Tallahassee Tennis Challenger. This was his first title on clay and put him back in the Top 200 of the ATP rankings. The title also helped him clinch the French Open Wild Card Challenge to earn a wild card into the main draw of the French Open. In his debut at the tournament, he was beaten by compatriot John Isner.
Noah Rubin (tennis)