Bellucci began the year qualifying for 2014 Australian Open, in which he won in the first round against German Julian Reister and lost in second to world no.
10 Jo-Wilfried Tsonga in straight sets.
Then he qualified for the 2014 Royal Guard Open in Viña del Mar and lost in the 1st round to Japanese qualifier Taro Daniel.
The Brazilian lost in the Q1 of Buenos Aires and followed with a quarterfinal campaign at the inaugural Rio Open losing to 3rd ranked David Ferrer after winning the first set.
Got to semifinals in São Paulo, losing to argentinian Federico Delbonis in three sets.
Lost three matches in a row, respectively at Miami, Monte Carlo and Bucharest until he passed the quali in Munich and got as far as the quarterfinal stage, losing to 15th ranked Fabio Fognini.

Lost in Q2 of Madrid and at Roland Garros won in the 1st round against German Benjamin Becker in five sets (6–2, 6–4, 3–6, 4–6, 6–2) and lost in 2nd round again to Fognini in straight sets.
Lost in 2nd round of Marburg Challenger to Swiss Henri Laaksonen and Q1 of Wimbledon to aussie and former junior number 1, Luke Saville.
Lost in the 2nd round of both Braunschweig and Scheveningen challengers to Philipp Petzschner and Matteo Viola.
As a lucky loser, reached the 2nd round in Hamburg, but lost to Spaniard Pablo Andújar and followed with a quarterfinal showing at Gstaad losing to Juan Mónaco.
Lost in the 1st round of Winston-Salem to Frank Dancevic.

At the US Open, Bellucci defeated Nicolas Mahut in straight sets before falling to No.
4 ranked, Stan Wawrinka in the second round after giving a good fight to the grand slam champion, winning the third set and being a break up in the fourth before losing  by 3–6, 4–6, 6–3, 6–7.
In the Davis Cup play-offs, Bellucci was a key component of a stunning victory of Brazil over Spain in the clay courts of São Paulo.
The Brazilian was two sets down against known foe Pablo Andujar before coming back to win 3–6, 6–7, 6–4, 7–5, 6–3.
After the doubles team of Marcelo Melo and Bruno Soares made it to a 2–1 advantage for Brazil, Bellucci finished the job and clinched the place for his country in the 2015 World Group by winning a nervous four setter against 15th ranked Roberto Bautista Agut (6–4, 3–6, 6–3, 6–2) and Brazil 3–1 Spain.
After the match Thomaz fell to his knees, crying, as the same crowd that booed him one year earlier, applauded as their hero consolidated this historic win.
Bellucci reached the quarterfinal stage at Vienna after defeating third seed Feliciano Lopez and again at Valencia after winning over Mikhail Youzhny and Bautista Agut.
Therefore, the Brazilian closed the season back in the top 100, ranked 65 of the world.
Bellucci began the year qualifying for 2014 Australian Open, in which he won in the first round against German Julian Reister and lost in second to world no. 10 Jo-Wilfried Tsonga in straight sets. Then he qualified for the 2014 Royal Guard Open in Viña del Mar and lost in the 1st round to Japanese qualifier Taro Daniel. The Brazilian lost in the Q1 of Buenos Aires and followed with a quarterfinal campaign at the inaugural Rio Open losing to 3rd ranked David Ferrer after winning the first set. Got to semifinals in São Paulo, losing to argentinian Federico Delbonis in three sets. Lost three matches in a row, respectively at Miami, Monte Carlo and Bucharest until he passed the quali in Munich and got as far as the quarterfinal stage, losing to 15th ranked Fabio Fognini.
Lost in Q2 of Madrid and at Roland Garros won in the 1st round against German Benjamin Becker in five sets (6–2, 6–4, 3–6, 4–6, 6–2) and lost in 2nd round again to Fognini in straight sets. Lost in 2nd round of Marburg Challenger to Swiss Henri Laaksonen and Q1 of Wimbledon to aussie and former junior number 1, Luke Saville. Lost in the 2nd round of both Braunschweig and Scheveningen challengers to Philipp Petzschner and Matteo Viola. As a lucky loser, reached the 2nd round in Hamburg, but lost to Spaniard Pablo Andújar and followed with a quarterfinal showing at Gstaad losing to Juan Mónaco. Lost in the 1st round of Winston-Salem to Frank Dancevic.
At the US Open, Bellucci defeated Nicolas Mahut in straight sets before falling to No. 4 ranked, Stan Wawrinka in the second round after giving a good fight to the grand slam champion, winning the third set and being a break up in the fourth before losing  by 3–6, 4–6, 6–3, 6–7. In the Davis Cup play-offs, Bellucci was a key component of a stunning victory of Brazil over Spain in the clay courts of São Paulo. The Brazilian was two sets down against known foe Pablo Andujar before coming back to win 3–6, 6–7, 6–4, 7–5, 6–3. After the doubles team of Marcelo Melo and Bruno Soares made it to a 2–1 advantage for Brazil, Bellucci finished the job and clinched the place for his country in the 2015 World Group by winning a nervous four setter against 15th ranked Roberto Bautista Agut (6–4, 3–6, 6–3, 6–2) and Brazil 3–1 Spain. After the match Thomaz fell to his knees, crying, as the same crowd that booed him one year earlier, applauded as their hero consolidated this historic win. Bellucci reached the quarterfinal stage at Vienna after defeating third seed Feliciano Lopez and again at Valencia after winning over Mikhail Youzhny and Bautista Agut. Therefore, the Brazilian closed the season back in the top 100, ranked 65 of the world.
Thomaz Bellucci