[3] In high school, he also played doubles with his brother Eric, and they won the team state championship together in Jack's sophomore year.

[4] Jack went on to win two more team state championships after Eric graduated and began playing college tennis at the University of Nebraska.

[citation needed] Sock appeared at the Match for Africa 5 alongside Roger Federer, Bill Gates and Savannah Guthrie on March 5, 2018 at the SAP Center in San Jose, California.

The friendly, best-of-three sets, charity exhibition match raised $2.5 million to benefit children's education in Africa, with net proceeds going to the Roger Federer Foundation.

[16] Sock's real breakthrough came in the mixed doubles, however, where he advanced to the final alongside Melanie Oudin, defeating the defending champions Bob Bryan and Liezel Huber in the second round.

[17] In the final, Sock and Oudin defeated Gisela Dulko and Eduardo Schwank in three sets to win their first Grand Slam title, both individually and together.

[24] However, he received a wildcard entry into the U.S. National Indoor Tennis Championships, in which he gained his first wins of the season, reaching the quarterfinals for the second time in his career.

[25] In the doubles competition at the same tournament, Sock teamed up with James Blake, also a wildcard entry, reaching the final, where the pair lost to the Bryan brothers.

At Wimbledon, Sock at the last moment teamed up with Canadian Vasek Pospisil, and they won the men's doubles title in a five-set final against the top seeds, Bob and Mike Bryan.

His second tournament was the 2015 Miami Open, in which he won his first two matches, including beating 21st seed Fabio Fognini, before losing to Dominic Thiem in the third round.

He then competed in the 2015 Mutua Madrid Open in Spain, advancing to the second round by beating wildcard Pablo Andújar in straight sets, before losing to 12th seed Jo-Wilfried Tsonga.

For the second straight year, he and Pospisil finished 9th in the ATP Doubles Race to London rankings, just barely failing to qualify for the year-end championship tournament.

Sock began his season at the 2016 Hopman Cup, representing the USA alongside Serena Williams, who was ultimately replaced by Victoria Duval due to injury.

Sock then followed this performance with an even better result at the Auckland Open by reaching the final for the second year in a row, this time winning the title against João Sousa.

In February, Sock returned home to the United States where he helped the Davis Cup team sweep their 1st-round rubber against Switzerland.

After a relatively quiet middle of the season, Sock finished the year strong by winning the biggest tournament of his career at the Paris Masters, defeating Filip Krajinović in the final.

[33] In the final tournament of the year, Sock rebounded from an opening match loss to Roger Federer to finish second in the Boris Becker group.

Struggling with fitness issues, he won just one match between those two tournaments and the Australian Open, where he lost in the first round to Yūichi Sugita for the third time in the last six months.

[34][35] In particular, the tournament organizers in Auckland criticized Sock for showing a lack of effort in his match against Peter Gojowczyk and considered withholding the $100,000 appearance fee they promised him for playing in the event.

[36] Sock's poor start to the season continued at the 2018 Delray Beach Open, where as the top seed and defending champion he lost in the second round to Reilly Opelka ranked number 228.

However, Sock won the doubles title with his partner, John Isner, after recording impressive victories over Ivan Dodig and Rajeev Ram, Oliver Marach and Mate Pavić, and Bob and Mike Bryan.

In singles at the 2018 Miami Open, Sock recorded a 6–3, 7–6 win over Yuki Bhambri the round of 64, but then fell 7–5, 6–7, 3–6 to rising star, Borna Ćorić.

Sock and his partner, Nicholas Monroe, failed to record a win in doubles with a 1–6, 6–7 loss to Jean-Julien Rojer and Horia Tecău in the round 32.

Continuing his partnership with Mike Bryan, he achieved his first US Open Men's doubles trophy, defeating Łukasz Kubot and Marcelo Melo in straight sets.

The final doubles match of the Laver Cup saw him and countryman John Isner triumph over Roger Federer and Alexander Zverev over two sets and a tight super-tiebreak.

Following the tournament, he suffered an injury during a practice to two ligaments in his thumb, which required operation and left him struggling to complete tasks such as opening bottles or brushing his teeth.

[42] In doubles, partnering with Jackson Withrow, he reached the quarterfinals defeating the Bryan Brothers en route but lost to 15th seed Jamie Murray/Neal Skupski.

There, he defeated 8th seed and defending champion Radu Albot which would be his first ATP match win since the 2019 Laver Cup and before that the 2018 Rolex Paris Masters.

Sock started off the year by playing in challenger events from March to June which resulted in a doubles title at the Orlando Open partnering with Mitchell Krueger.

At the Little Rock Challenger, Sock won his first singles title of any kind in close to four years defeating 3rd seed Emilio Gómez in the final.