Miami Heat (2008–2015) After working out for 13 teams, Chalmers was drafted with the 34th overall pick in the second round of the
2008 NBA draft by the
Minnesota Timberwolves. When asked immediately after being drafted how many times he had watched his overtime-forcing three-pointer against
Memphis in the
NCAA championship, Chalmers responded, "a million times." The rights to Chalmers were later included in a trade with the
Miami Heat. The Heat signed him on July 8.
2008–09 season Chalmers started all 82 regular season games his rookie year and finished the season averaging 10 points, 4.9 assists, 2.8 rebounds, 2 steals, and 32 minutes per game. His two steals per game ranked number one among all rookies and the fourth highest among all players. On November 5, 2008, in just his fourth NBA game, Chalmers set a franchise record for steals in a game with nine.
2009–10 season After having not missed a game up until the January 30 game against the
Milwaukee Bucks, Chalmers missed his first game in his two-year career. The next day, he was ruled out indefinitely with a torn ligament in his left thumb. Chalmers returned to action on February 19 against the
Memphis Grizzlies and played out the remainder of the season and the playoffs.
2010–11 season Upon the Heat's acquisition of
LeBron James in July 2010, Chalmers handed over No. 6 to James after wearing it during his first two NBA seasons, and changed to his collegiate number of 15. In Game 5 of the
2011 NBA Finals, Chalmers made a half-court shot at the buzzer of the first quarter to give the Heat a 31–30 lead. However, the Heat went on to lose the game to the
Dallas Mavericks 112–103 and trailed in the series 2–3. Chalmers had 15 points, 4 rebounds, 2 assists, and 1 steal. In Game 6, the Heat fell to the Mavericks, as they lost the series 4–2.
2011–12 season On June 15, 2011, the Heat extended a qualifying offer to Chalmers, making him a restricted free agent in the offseason. On December 9, 2011, Chalmers re-signed with the Heat on a three-year, $12 million contract. On February 15, 2012, Chalmers was named a participant in the 2012
NBA All-Star Weekend Three-Point Shootout. He was eliminated in the first round. Chalmers was highly praised for his 25-point performance in Game 4 of the
2012 NBA Finals. He scored 12 points in the fourth quarter to help the Heat win the game. In Game 5 of the NBA Finals, Chalmers recorded 10 points, seven assists, and two rebounds in 34 minutes of action as he helped the Heat win the 2012 NBA championship. It was Chalmers' first NBA title.
2012–13 season On January 12, 2013, Chalmers scored a career-high 34 points against the
Sacramento Kings, making 10 three-pointers. He tied the Heat's record for most three-pointers in a game. On June 9, 2013, during Game 2 of the NBA Finals against the
San Antonio Spurs, Chalmers led all scorers with 19 points as the Heat tied the series 1–1 with a 103–84 victory. In the sixth game of the series, on June 18, he scored 20 points to help the Heat secure a 103–100 win. He won his second championship on June 20, as the Heat defeated the Spurs to conclude an intense seven-game series.
2013–14 season On April 4, 2014, Chalmers scored a season-high 24 points in the 121–122 loss to the Minnesota Timberwolves. He finished the regular season with averages of 9.8 points and 4.9 assists in 73 games. The Heat advanced to the
2014 NBA Finals to record their fourth straight Finals appearance. The Heat faced the San Antonio Spurs again, but unlike past Finals series, Chalmers struggled and was replaced in the starting lineup by
Ray Allen in Game 5. The Heat ended up losing the series in five games.
2014–15 season On July 14, 2014, Chalmers re-signed with the Heat. On November 22, 2014, he scored a season-high 24 points in the 99–92 win over the Orlando Magic.
Memphis Grizzlies (2015–2018) On November 10, 2015, Chalmers was traded, along with
James Ennis, to the
Memphis Grizzlies in exchange for
Jarnell Stokes and
Beno Udrih. He made his debut for the Grizzlies three days later, scoring 11 points off the bench in a 101–100 win over the
Portland Trail Blazers. On November 16, 2015, he scored a season-high 29 points in a 122–114 win over the
Oklahoma City Thunder. On March 10, 2016, he was ruled out for the rest of the season after rupturing his right Achilles tendon in Memphis' 116–96 loss to the
Boston Celtics the previous night. He was subsequently waived by the Grizzlies. In November 2016, after recovering from the Achilles injury, Chalmers was ready to make his comeback. However, he went unsigned throughout the 2016–17 season. On July 19, 2017, Chalmers re-signed with the Grizzlies.
Virtus Bologna (2019) On March 3, 2019, Chalmers joined
Virtus Bologna of the Italian
Lega Basket Serie A (LBA), signing for the rest of the season with an option to extend it for the 2019–20 season. In the 10 games he played for Virtus (including the
LBA and the
Champions League), he averaged 7.8 points, 2.3 rebounds, and 3 assists per game. Chalmers won the
2019 FIBA Champions League title with Virtus.
AEK Athens (2019–2020) To stay in shape, Chalmers returned to the US during the summer to join the
Big3 League. On November 4, 2019, Chalmers joined
AEK Athens of the
Greek Basket League, signing a two-month contract with an option to extend it for the rest of the season, which AEK exercised on January 16.
Aris (2020–2021) On September 21, 2020, Chalmers signed a one-year contract with
Aris Thessaloniki of the Greek Basket League.
Indios de Mayagüez (2021) On September 27, 2021, Chalmers signed with
Indios de Mayagüez of the
Baloncesto Superior Nacional.
Grand Rapids Gold (2021) On December 18, 2021, Chalmers signed with the
Grand Rapids Gold of the
NBA G League.
Sioux Falls Skyforce (2022) On December 31, 2021, Chalmers returned to the
Miami Heat on a 10-day contract via the hardship exemption after the team placed 5 players in the NBA health and safety protocols. However, he never played a game for the team. On January 14, 2022, Chalmers was acquired by the
Sioux Falls Skyforce.
Zamboanga Valientes (2023) In January 2023, Chalmers signed with
Zamboanga Valientes in the
ASEAN Basketball League. ==NBA career statistics==