1 ranked college freshman, he finished the season as an All-American and the runner-up in the 2015 NCAA singles championship.

In October 2022, Rubin announced he would retire from tennis and pursue a career as a professional pickleball player.

His father was the top player on the tennis team at Martin Van Buren High School in Queens.

[19] The month after hoisting the trophy at Wimbledon, Rubin played in and won the 2014 U.S. Tennis Association's Boys 18s National Championships in both singles and doubles (with close friend Stefan Kozlov).

[13] The latter success came with two big bonuses of main-draw wild cards into the singles and doubles events at the US Open.

With his wild card, Rubin entered his second career Grand Slam event as the lowest-ranked non-PR player (328th overall)[26] in the main draw of the 2016 Australian Open, where he beat the 17th-seeded Benoit Paire in three tiebreaks in the first round.

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,[27][28] Rubin returned to form in October, reaching his second career Challenger final at Stockton.

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.

At this tournament, he greatly improved on his second-round result from the previous 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.

His last career professional match was in the 2022 Citi Open where he lost 6–2, 6–0 to Taro Daniel in the first round of qualifying.

[32] On September 19, 2022, Rubin, in an Instagram post announced he would be taking an indefinite break from professional tennis.

In the post, Rubin did not rule out returning to professional tennis, but he stated he will be involved with a number of endeavors including "documentaries, clothing lines [and] clubs."

[33] Rubin has an Instagram account that has met with “modest success,” Behind the Racquet, where players share personal struggles of living on the professional tour.

[34] Rubin has found the process to be therapeutic for dealing with the realities of “often lonely, physically taxing life” of professional tennis.