Martínez Sánchez started the year playing at the 2009 Australian Open, the first Grand Slam of the year.
In the first round, she upset the 32nd seed Tamarine Tanasugarn 7–5, 6–3.
She then defeated Akgul Amanmuradova 6–2, 6–4 but lost in the third round to compatriot Carla Suárez Navarro 6–1, 6–4.
In doubles, she and Nuria Llagostera Vives were seeded 11th and defeated 6th seeds Yan Zi and Zheng Jie in the third round but they lost a tough match in the quarterfinals to Nathalie Dechy and Mara Santangelo 3–6, 7–6, 7–6.

María José next played at the 2009 Copa Sony Ericsson Colsanitas where she was seeded 7th.
She defeated Anastasiya Yakimova, Arantxa Parra Santonja and Betina Jozami to reach the semi-finals where she won a close match against Patricia Mayr 7–5, 7–5.
She captured her first WTA singles titl when she defeated 3rd seed Gisela Dulko 6–3, 6–2 in the final.
In doubles, Martínez Sánchez and Llagostera Vives were the top seeds and they reached the final where they beat second seeds Gisela Dulko and Flavia Pennetta 7–5, 3–6, [10–7] to win their first doubles title of the year.

She reached the third round at Roland Garros.
In that match against Serena Williams she was accused of cheating and poor sportsmanship.

Martínez Sánchez won her second singles title at the year at the 2009 Swedish Open.
On the way she defeated 4th seed Kaia Kanepi, Carla Suárez Navarro and Gisela Dulko before beating top seed and World No.
9 Caroline Wozniacki 7–5, 6–4 in the final.

Martínez Sánchez and her partner Nuria Llagostera Vives won the year ending championships in doubles.
As the third seeds, they defeated Venus Williams and Serena Williams 2–6, 6–4, [10–8] before winning the biggest title of their careers against World No.
1's Cara Black and Liezel Huber 7–6, 5–7, [10–8] in the final.

Maria qualified to play at the 2009 Commonwealth Bank Tournament of Champions in Bali.
She recovered from a first set deficit to beat Szávay in 3 sets 4–6, 6–4, 6–0 in her second group round robin match she beat Stosur in straight sets 7–6, 7–5 where Stosur served a 208kmps world record serve.
In the semifinal she lost against Aravane Rezaï 6–2, 6–3, who clearly outplayed her on that day.

Overall, Martínez Sánchez had the greatest year of her career.
The highlights were winning two singles WTA titles at Bogotá and Båstad (Sweden)  and by reaching the third rounds at the Australian Open, French Open, US Open.
She ended the year ranked World No.
30.

In doubles, she won seven titles with Nuria Llagostera Vives at Bogotá, Acapulco, Barcelona, Palermo, Toronto, New Haven and the most important, the WTA Tour Championships in Doha.
She ended the year ranked World No.
5.
Martínez Sánchez started the year playing at the 2009 Australian Open, the first Grand Slam of the year. In the first round, she upset the 32nd seed Tamarine Tanasugarn 7–5, 6–3. She then defeated Akgul Amanmuradova 6–2, 6–4 but lost in the third round to compatriot Carla Suárez Navarro 6–1, 6–4. In doubles, she and Nuria Llagostera Vives were seeded 11th and defeated 6th seeds Yan Zi and Zheng Jie in the third round but they lost a tough match in the quarterfinals to Nathalie Dechy and Mara Santangelo 3–6, 7–6, 7–6.
María José next played at the 2009 Copa Sony Ericsson Colsanitas where she was seeded 7th. She defeated Anastasiya Yakimova, Arantxa Parra Santonja and Betina Jozami to reach the semi-finals where she won a close match against Patricia Mayr 7–5, 7–5. She captured her first WTA singles titl when she defeated 3rd seed Gisela Dulko 6–3, 6–2 in the final. In doubles, Martínez Sánchez and Llagostera Vives were the top seeds and they reached the final where they beat second seeds Gisela Dulko and Flavia Pennetta 7–5, 3–6, [10–7] to win their first doubles title of the year.
She reached the third round at Roland Garros. In that match against Serena Williams she was accused of cheating and poor sportsmanship.
Martínez Sánchez won her second singles title at the year at the 2009 Swedish Open. On the way she defeated 4th seed Kaia Kanepi, Carla Suárez Navarro and Gisela Dulko before beating top seed and World No. 9 Caroline Wozniacki 7–5, 6–4 in the final.
Martínez Sánchez and her partner Nuria Llagostera Vives won the year ending championships in doubles. As the third seeds, they defeated Venus Williams and Serena Williams 2–6, 6–4, [10–8] before winning the biggest title of their careers against World No. 1's Cara Black and Liezel Huber 7–6, 5–7, [10–8] in the final.
Maria qualified to play at the 2009 Commonwealth Bank Tournament of Champions in Bali. She recovered from a first set deficit to beat Szávay in 3 sets 4–6, 6–4, 6–0 in her second group round robin match she beat Stosur in straight sets 7–6, 7–5 where Stosur served a 208kmps world record serve. In the semifinal she lost against Aravane Rezaï 6–2, 6–3, who clearly outplayed her on that day.
Overall, Martínez Sánchez had the greatest year of her career. The highlights were winning two singles WTA titles at Bogotá and Båstad (Sweden)  and by reaching the third rounds at the Australian Open, French Open, US Open. She ended the year ranked World No. 30.
In doubles, she won seven titles with Nuria Llagostera Vives at Bogotá, Acapulco, Barcelona, Palermo, Toronto, New Haven and the most important, the WTA Tour Championships in Doha. She ended the year ranked World No. 5.
María José Martínez Sánchez