July 11: The Heat signed Ray Allen, the NBA's all-time leader in three-pointers made.
October 30: The Heat opened the season with a 120-107 home victory over the Boston Celtics. The previous year's players received their championship rings and the team raised their 2nd championship banner into the American Airlines Arena rafters.
November 21: Udonis Haslem surpassed Alonzo Mourning in all-time rebounding for the Miami Heat and became the first undrafted player in NBA history to lead a franchise in rebounding. Adding to this accomplishment, Haslem has now starred in the most Miami Heat games played, one more than fellow captain Dwyane Wade.
November 24: Chris Bosh surpassed the 13,000-point plateau.
December 15: For the first time in franchise history, all 13 active players scored at least three points and converted one made field goal. 
December 25: Mike Miller surpassed the 10,000-point plateau.
February 23: Dwyane Wade surpassed the 16,000-point plateau.
March 2: Juwan Howard signed a 10-day contract, re-joining the Heat.
March 5: The Heat beat the Minnesota Timberwolves 97-81 to extend their winning streak to a franchise-record 15 wins in a row, improving their record to 44-14.
March 8: The Heat beat the Philadelphia 76ers 102-93, becoming the first team in the league to clinch a playoff berth and extending their winning streak to 17. They also marked their best record through 60 games in franchise history at 46-14.
March 10: For the first time in franchise history, the Heat beat every single team in the NBA with their victory against the Indiana Pacers. Miami was able to defeat all 29 opponents by their 61st game.
March 18: The Heat came back from a 17-point deficit to beat the Boston Celtics 105-103 to clinch the Southeast Division for the third consecutive year and extend their winning streak to 23 games, the second longest in NBA history.
March 20: The Heat overcame a league high 27-point third-quarter deficit beat the Cleveland Cavaliers 98-95 to extend their winning streak to 24 games.
March 22: The Heat overcame an 11-point deficit to beat Detroit Pistons 103-89 to extend their winning streak to 25 games. This is the third consecutive game in which the Heat came back from double digit deficits, the fifth during the streak, and 11th of the season. Juwan Howard signed for the reminder of the season.
March 24: The Heat overcame an 11-point deficit with Dwyane Wade inactive to beat Charlotte Bobcats 109-77 to extend their winning streak to 26 games. This is the fourth consecutive game in which the Heat came back from double digit deficits, the 6th during the streak, and 12th of the season.
March 25: The Heat beat Orlando to extend their winning streak to 27 games.
March 27: The Heat fall 101-97 to the Chicago Bulls, ending their winning streak at 27.
March 29: The Heat defeated the New Orleans Hornets 108-89, clinching the best record in the Eastern Conference for the third time in franchise history.
March 31: The Heat defeated the San Antonio Spurs 88-86 without all-stars LeBron James and Dwyane Wade, along with Mario Chalmers, becoming the first team in NBA history to win at least 17 games in a calendar month.
April 10: The Heat defeated the Washington Wizards 103-98, clinching the best record in the NBA and home-court advantage throughout the playoffs for the first time in franchise history, and improving their record to 62-16 to set a franchise record for wins in a season.
April 14: The Heat defeated the Chicago Bulls 105-93, avenging the March 27 loss and winning their 36th game at home, the most in franchise history.
April 15: The 16th back to back game night. The Heat earned a 15-1 record (.938) on the second night of a back-to-back set this season, tying Dallas (2006-07) for the best record on the second night of a back-to back set in NBA history.
April 17: The Heat concluded the regular season with a 105-93 victory over the Orlando Magic. They finished the season with a record of 66-16, going 37-4 at home and 29-12 on the road.
April 28: The Heat defeated the Milwaukee Bucks in Game 4 of the Eastern Conference First Round, advancing to the Conference Semi-Finals.
May 15: The Heat defeated the Chicago Bulls in Game 5 of the Eastern Conference Semi-Finals, advancing to the Conference Finals.
June 3: The Heat defeated the Indiana Pacers in Game 7 of the Eastern Conference Finals, advancing to the NBA Finals for a third consecutive season, making them the first Eastern Conference team to accomplish this since the Chicago Bulls (1996-1998). Dwyane Wade also snapped a 12-game streak where he scored less than 20 points.
June 18: The Heat came back from a 13-point deficit in the 4th quarter to defeat the San Antonio Spurs in Game 6 of the NBA Finals, with LeBron James scoring 18 points in the period and Ray Allen hitting a 3 to tie the game with 5 seconds left in regulation.
June 20: The Heat defeated the San Antonio Spurs in the NBA Finals to repeat as NBA Champions.
The following records were set or tied by the Heat this season-
Most wins in a month: The Heat went 17-1 in March 2013, becoming the first team to win 17 games in a single calendar month in NBA history.
Overtime in Postseason: The HEAT’s 103-100 overtime win vs. SA on June 18, 2013 improved their all-time postseason overtime record to 8-1 (.889). Their .889 postseason winning percentage is the best among teams with at least three overtime games played and the second-highest among all teams. 
DOUBLE-DIGIT wins in Postseason: The HEAT’s 16-point, 109-93, win in Game Four of the NBA Finals at SA on June 13, 2013 was Miami’s 12th double-figure win in the 2013 postseason. The 12 double-digit wins are the most by any team during a single postseason in NBA history. The previous record was 11, held by five different teams, each winning the NBA Championship that postseason. 
Highest Field Goal Made Percentage, post season: Chris "Birdman" Andersen shot 80.7 percent (46-of-57) from the field in the 2013 postseason. He has become the first player in NBA postseason history to take at least 35 shots and shoot better than 75 percent from the field.
SIX AND SEVEN over 30 points: LeBron James scored 32 points in Game Six of the NBA Finals on June 18, 2013 and then made 37 points in Game Seven on June 20, 2013. According to Elias Sports Bureau, he became the first player in NBA history to score consecutive 30-point games to help rally his team from a 3-2 series deficit to win an NBA title. 
GAME SEVEN over 30 Points: LeBron James finished the 2013 postseason by recording his fourth-straight 30-point Game Seven by scoring 37 points vs. SA in the NBA Finals. He had previously scored 32 points vs. IND on June 3, 2013, 31 points vs. BOS on June 9, 2012 and 45 points at BOS on May 18, 2008. The Elias Sports Bureau reports he has tied the record of the only other player to score at least 30 points in four consecutive Game Seven’s, Elgin Baylor (33 at STL on 3/26/60, 39 at STL on 4/1/61, 41 at BOS on 4/18/62, 35 vs. STL on 4/11/63 & 33 vs. STL on 4/15/66). 
Highest Scoring average in game sevens: Lebron James is averaging 34.4 points in Game Seven’s of the postseason during his career, currently the best average in NBA history. 
Most 3 point FG in Postseason: Ray Allen owns the record for most 3 point field goals in the postseason - 352. 
Most 4 point plays in a Finals game, 2: On June 16, 2013, Ray Allen converted two free throws after making three point field goals, one at the 5:08 mark in the 2nd quarter, and the other with 8:37 left in the 4th quarter. There had previously been only 12 four point plays in the NBA Finals history. 
Team Leader in Points, Rebounds, and Assists: LeBron James’ 18 points, 18 rebounds and 10 assists vs. SA on June 6, 2013 was the 28th time he has led his team outright (no ties) in each of those categories during the playoffs, the most in NBA postseason history. In addition, he has been the outright game-high leader (no ties) in each of those categories eight times, also the most in NBA postseason history. His eight such games are more than the combined total of the next three players to achieve the feat. 
25-10-8: LeBron James’ 32 points, 10 rebounds and 11 assists vs. SA on June 18, 2013 marked his 15th postseason 25-point, 10-rebound, eight-assist game,the most in NBA postseason history. According to Elias, second on this list is Oscar Robertson with 10 such games. 
BACK-TO-BACKS: The HEAT recorded a 15-1 record (.938) on the second night of a back-to-back set in the 2012-13 season, tying for the best record on the second night of a back-to back set in NBA history. The Dallas Mavericks also finished 15-1 (.938) in such games during the 2006-07 season.