Monaco began his 2012 campaign at the 2012 Australian Open as the 25th seed, but was upset by Philipp Kohlschreiber in the first round.
He then competed in the 2012 VTR Open as the top seed.
He received a first-round bye, then defeated Igor Andreev, Albert Montañés, Jérémy Chardy, and finally Carlos Berlocq in the final.
This was his fourth title and first since 2007, It also ended his seven consecutive runner-up finishes.
He then represented Argentina against Germany in the first round of the Davis Cup and won his only match against Philipp Petzschner.
He then played at the 2012 Copa Claro, losing to compatriot David Nalbandian.
He then retired in his first-round match at the 2012 Abierto Mexicano Telcel due to dehydration against Albert Ramos.
At the first Masters of the year, the 2012 BNP Paribas Open, he fell in the third round to eventual finalist John Isner.
At the 2012 Sony Ericsson Open, he fell to world no.
1 and defending champion Novak Djokovic in his second Masters semifinals, after wins over Lu Yen-hsun, 14th seed Gaël Monfils, 31st seed Andy Roddick, and 8th seed Mardy Fish.
This performance pushed him to no.
16 in the world, his highest ranking since May 2008.

He then played in the 2012 U.S. Men's Clay Court Championships as the 4th seed and wild card.
He beat Tatsuma Ito, Kevin Anderson, and Michael Russell to advance to the final.
In the final, he faced second seed John Isner and won, to claim his second title of the year and fifth overall.
He also matched his career-high ranking of no.
14 in the world after the win.
He then played at the 2012 Monte-Carlo Rolex Masters, where he retired due to a right ankle injury in his first-round match against Robin Haase while leading by a break in the third.
The injury also forced him to withdraw from the Barcelona Open  and the Mutua Madrid Open.

He was seeded 14th in Rome and won his first two matches against Adrian Ungur, and Radek Štěpánek, before losing to defending champion and world no.
1 Novak Djokovic.

At the French Open, he first faced Frenchman Guillaume Rufin.
He then cruised passed Lukáš Rosol.
In the third round he had a tough match against the big-serving Canadian Milos Raonic and converted 3/16 break points and saved all break points he faced, the Argentinian won the match.
He made it to the fourth round, where he lost to Rafael Nadal.
He was broken twice in the first set and pulled a double bagel in the second and third, although he had a couple of break opportunities of his own in the second.

At the 2012 Wimbledon Championships, he finally notched his first career win on grass by beating compatriot Leonardo Mayer in the first round.
He then followed it up with a win over Jérémy Chardy.
In the third round, he lost to Viktor Troicki despite leading the 1st set by a break and coming back from a break in the second.

Juan Mónaco then played the 2012 MercedesCup, he cruised past Tobias Kamke and Pavol Červenák in straight sets after receiving a bye in the first round.
He then faced Guillermo García-López and was leading 5–0 in the third set; he then lost 5 games in a row but eventually won 7–5.
In the final he lost to top seed Janko Tipsarević, even after coming back from 1–4 in the second and had momentum in the third.
He then played at the 2012 International German Open, he first met Cedrik-Marcel Stebe in the first round and won in three tight sets, being down 5–4 in the final set with Stebe serving for the match.
He then won in straight sets against Daniel Muñoz de la Nava and Jérémy Chardy.
In the semifinals he faced top seed Nicolás Almagro losing the first set, he came back and won the second.
He was down 4–2 in the third but won the last 4 games to advance to the final.
In the final he faced local man and wild card Tommy Haas and won being 4–1 down in the first.
With the win he entered the top ten for the first time in his career.

He then played the Summer Olympics defeating David Goffin before losing to Feliciano López in the following round.
He then suffered 4 loses in a row, losing in the second round of 2012 Rogers Cup to Mardy Fish, first ro
Monaco began his 2012 campaign at the 2012 Australian Open as the 25th seed, but was upset by Philipp Kohlschreiber in the first round. He then competed in the 2012 VTR Open as the top seed. He received a first-round bye, then defeated Igor Andreev, Albert Montañés, Jérémy Chardy, and finally Carlos Berlocq in the final. This was his fourth title and first since 2007, It also ended his seven consecutive runner-up finishes. He then represented Argentina against Germany in the first round of the Davis Cup and won his only match against Philipp Petzschner. He then played at the 2012 Copa Claro, losing to compatriot David Nalbandian. He then retired in his first-round match at the 2012 Abierto Mexicano Telcel due to dehydration against Albert Ramos. At the first Masters of the year, the 2012 BNP Paribas Open, he fell in the third round to eventual finalist John Isner. At the 2012 Sony Ericsson Open, he fell to world no. 1 and defending champion Novak Djokovic in his second Masters semifinals, after wins over Lu Yen-hsun, 14th seed Gaël Monfils, 31st seed Andy Roddick, and 8th seed Mardy Fish. This performance pushed him to no. 16 in the world, his highest ranking since May 2008.
He then played in the 2012 U.S. Men's Clay Court Championships as the 4th seed and wild card. He beat Tatsuma Ito, Kevin Anderson, and Michael Russell to advance to the final. In the final, he faced second seed John Isner and won, to claim his second title of the year and fifth overall. He also matched his career-high ranking of no. 14 in the world after the win. He then played at the 2012 Monte-Carlo Rolex Masters, where he retired due to a right ankle injury in his first-round match against Robin Haase while leading by a break in the third. The injury also forced him to withdraw from the Barcelona Open  and the Mutua Madrid Open.
He was seeded 14th in Rome and won his first two matches against Adrian Ungur, and Radek Štěpánek, before losing to defending champion and world no. 1 Novak Djokovic.
At the French Open, he first faced Frenchman Guillaume Rufin. He then cruised passed Lukáš Rosol. In the third round he had a tough match against the big-serving Canadian Milos Raonic and converted 3/16 break points and saved all break points he faced, the Argentinian won the match. He made it to the fourth round, where he lost to Rafael Nadal. He was broken twice in the first set and pulled a double bagel in the second and third, although he had a couple of break opportunities of his own in the second.
At the 2012 Wimbledon Championships, he finally notched his first career win on grass by beating compatriot Leonardo Mayer in the first round. He then followed it up with a win over Jérémy Chardy. In the third round, he lost to Viktor Troicki despite leading the 1st set by a break and coming back from a break in the second.
Juan Mónaco then played the 2012 MercedesCup, he cruised past Tobias Kamke and Pavol Červenák in straight sets after receiving a bye in the first round. He then faced Guillermo García-López and was leading 5–0 in the third set; he then lost 5 games in a row but eventually won 7–5. In the final he lost to top seed Janko Tipsarević, even after coming back from 1–4 in the second and had momentum in the third. He then played at the 2012 International German Open, he first met Cedrik-Marcel Stebe in the first round and won in three tight sets, being down 5–4 in the final set with Stebe serving for the match. He then won in straight sets against Daniel Muñoz de la Nava and Jérémy Chardy. In the semifinals he faced top seed Nicolás Almagro losing the first set, he came back and won the second. He was down 4–2 in the third but won the last 4 games to advance to the final. In the final he faced local man and wild card Tommy Haas and won being 4–1 down in the first. With the win he entered the top ten for the first time in his career.
He then played the Summer Olympics defeating David Goffin before losing to Feliciano López in the following round. He then suffered 4 loses in a row, losing in the second round of 2012 Rogers Cup to Mardy Fish, first ro
Juan Mónaco