While in middle school she played for a male hockey team in Bethlehem, New York. Noteworthy teammates included her younger brother Robert Carpenter as well as Jonathan Clark, Sam Segal, Danny Golderman, and Jake Nussbaum. In fall 2007, she joined The Governor's Academy in South Byfield. Carpenter played for the Governor's Academy Varsity team as a 13-year-old. She racked up a total of 155 goals and 136 assists for 291 points over three years.
NCAA
On July 22, 2010, she committed to joining the Boston College Eagles women's ice hockey program in the fall of 2012. Alex recorded her 100th career point against UConn Feb 17 of her Sophomore season with BC. During her junior season at Boston College, she was the recipient of the 2015 Patty Kazmaier Award. Of note, Carpenter became the first player in the history of the Boston College Eagles program, and first player from the Hockey East conference to claim the award.
USA Hockey
She competed for Team USA in an Under-18 three-game exhibition series against Canada's best in Calgary, Alberta. She helped the US team win the 2009 Czech Challenge Cup in Prague. She scored a goal for Team USA in the gold medal game of the 2010 IIHF Women's Under 18 championships but had to settle for the silver medal. She was the youngest girl for Team USA in the tournament at fifteen-years-old. She finished the tournament with eight goals and one assist in five games. She was tied for second in team scoring behind Kendall Coyne. In 2013, she made the women's senior team and participated in the 2013 IIHF Women's World Championship and remained on Team USA for every following season, including the 2014 Olympics. Carpenter scored the game-winning overtime goal to lead the United States to a 1–0 win over Canada at the 2016 Women's World Hockey Championship. She was one of the final cuts from the 2018 Olympic team, but was brought back for the 2019 World Championship., Carpenter has participated in five IIHF World Championships with senior team, all of which ended with Team USA winning the tournament.
Professional
Carpenter was the first player drafted in the National Women's Hockey League's inaugural draft in 2015, selected by the New York Riveters. She returned for her senior season with Boston College and her rights were traded to the Boston Pride in April 2016. During the summer of 2016, Carpenter signed with the Boston Pride for a one-year, $19,500 contract, making her the highest paid player of the 2015 NWHL Draft class. Playing for Team Steadman, Carpenter recorded a goal and an assist at the 2nd NWHL All-Star Game. She finished the season as the second highest scorer in the league for the 2016–17 season. Following her season in the NWHL, Carpenter registered for the Canadian Women's Hockey League2017 draft and was drafted by one of the two Chinese expansion teams, Kunlun Red Star WIH based in Shenzhen, where her father Bobby Carpenter was also an adviser for the men's team HC Kunlun Red Star in the Kontinental Hockey League. After being cut from the United States Olympic team, she signed with Red Star on January 15, 2018. The following season, the two Chinese CWHL teams were merged and became the Shenzhen KRS Vanke Rays and Carpenter re-signed with the team. After the 2018–19 CWHL season, the league ceased operations and the team joined the Russian Women's Hockey League. She again chose to remain in China citing the better facilities and player support provided by the team than when she had been in the NWHL, supporting the boycott of North American leagues that had led to the formation of the Professional Women's Hockey Players Association.
Alex Carpenter was the first girl to play in the Morristown, New Jersey, Little League in 25 years and was the first girl to ever play as a 10-year-old.
