Juniors

As a junior, Smyczek reached as high as No. 14 in the world combined rankings in January 2005.

Pro tour

Smyczek reached the quarterfinals of the SAP Open in 2011, beating Kei Nishikori en route, but lost to Gaël Monfils. He qualified again in 2012, but lost to Mardy Fish in the first round.

In April 2012, he won his first Challenger title, defeating Frank Dancevic in the Tallahassee final, Dancevic retiring after losing the first set 5–7.

For the 2013 Australian Open, Smyczek earned entry as the last entry in the field and lucky loser, the highest-ranked player (ATP ranking of no. 128) who lost in the finals of qualifying. After beating Ivo Karlović in the first round, he lost to world no. 4 David Ferrer in the second round in four sets.

Tim lost the first round of the 2013 French Open qualifying. He fared better at Wimbledon; he made it to the third round of qualifying for the first time, losing to Matt Reid in four sets. Tim reached the doubles final of the 2013 Hall of Fame Tennis Championships with Rhyne Williams as his partner. In the final the American duo fell to Nicolas Mahut and his partner and fellow Frenchmen Edouard Roger-Vasselin. Tim made it to the third round of the Citi Open. He qualified for the Rogers Cup and made it to the second round.

At the 2015 Australian Open, Smyczek entered the main draw as a qualifier, and lost in a four-hour match that ended 7–5 in the fifth set against World No. 3 Rafael Nadal in the second round. In the final game of the match, he graciously allowed Nadal to repeat a crucial first serve when Nadal’s serve landed out, possibly due to a disturbance by a member of the crowd. Smyczek (not the chair umpire) initiated the decision for Nadal to repeat the first serve. Smyczek’s sportsmanship resulted in praise from Nadal and the crowd after the match.^[5] He would go on to achieve his career high rank of 68 in April.

In 2016 Smyczek made the quarterfinals in Houston and Delray Beach.^[6]

In 2018 Smyczek attained his best main tour result by reaching the semi-finals of Newport.^[7]

In 2019 Smyczek announced his plans to retire after the U.S. Open but was not granted a wild card. His last match was at the Citi Open.^[8][9]

Doubles: 1 (1 runner-up)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Loss	0–1	Jul 2013	Campbell's Hall of Fame Tennis Championships, United States	250 Series	Grass	Rhyne Williams	Nicolas Mahut Édouard Roger-Vasselin	7–6(7–4), 2–6, [5–10]

Singles (7–6)

Outcome	W–L	Date	Tournament	Surface	Opponent	Score
Runner-up	0–1	June 29, 2009	Winnetka, US	Hard	Alex Kuznetsov	4–6, 6–7(1–7)
Runner-up	0–2	March 22, 2010	Rimouski, Canada	Hard	Rik de Voest	0–6, 5–7
Runner-up	0–3	July 3, 2010	Winnetka, US	Hard	Brian Dabul	1–6, 6–1, 1–6
Winner	1–3	April 2, 2012	Tallahassee, US	Hard	Frank Dancevic	7–5 RET
Winner	2–3	November 17, 2012	Champaign, US	Hard(i)	Jack Sock	2–6, 7–6(7–1), 7–5
Runner-up	2–4	September 30, 2013	Sacramento, US	Hard	Donald Young	5–7, 3–6
Winner	3–4	November 10, 2013	Knoxville, US	Hard	Peter Polansky	6–4, 6–2
Runner-up	3–5	September 28, 2014	Napa, US	Hard	Sam Querrey	3–6, 1–6
Winner	4–5	February 7, 2015	Dallas, US	Hard(i)	Rajeev Ram	6–2, 4–1 RET
Runner-up	4–6	March 22, 2015	Irving, US	Hard	Aljaž Bedene	6–7(3–7), 6–3, 3–6
Winner	5–6	October 4, 2015	Tiburon, US	Hard	Denis Kudla	1–6, 6–1, 7–6(9–7)
Winner	6–6	November 5, 2017	Charlottesville, US	Hard	Tennys Sandgren	6–7(5–7), 6–3, 6–2
Winner	7–6	November 19, 2017	Champaign, US	Hard	Bjorn Fratangelo	6–2, 6–4

Doubles (0–1)

Outcome	W–L	Date	Tournament	Surface	Partner	Opponents	Score
Runner-up	0–1	April 28, 2013	Savannah, US	Clay	Michael Russell	Teymuraz Gabashvili Denys Molchanov	2–6, 5–7