Haruka Shimazaki was born in Saitama Prefecture, and began her entertainment career in 2009 by successfully auditioning for AKB48 in the 6th Kenkyūsei Audition (9th generation AKB48 audition). Her official nickname, Paruru, was coined by then fellow member Rumi Yonezawa. In the AKB48 17th single senbatsu election, which took place from May to June 2010, Shimazaki ranked 28th, the highest of all trainees. In June 2011 it was announced that she would be promoted to a newly created Team 4. In the AKB48 27th single senbatsu election, which took place from May to June 2012, Shimazaki ranked 23rd. In August 2012 she was transferred to Team B after Team 4 was disbanded. In September 2012 she won the 3rd AKB48 rock-paper-scissors tournament, held in Nippon Budokan, earning the center position in AKB48’s single “Eien Pressure,” which was released on December 5, 2012.

In 2012, Shimazaki appeared in the movie Gekijōban Shiritsu Bakaleya Kōkō, which was based on the 2012 TV series Shiritsu Bakaleya Kōkō. Later the same year she appeared together with Minami Takahashi in an automated external defibrillator (AED) training session, sponsored by the Japanese Red Cross. On February 23, 2013, she appeared on the cover of the April issue of the Japanese fashion magazine Smart. In October, the fashion magazine CanCam published an article about her signature look, dubbed the “troubled face make-up” (困り顔メイク, komari-gao meiku); this term went on to become one of the Top 50 Japanese Buzzwords of 2013, compiled by the publisher Jiyu Kokuminsha. In 2014, Shimazaki appeared in a recruiting commercial for the Japan Self-Defense Forces. Later that year, the phrase “salty treatment” (塩対応, shio taiō), which referred to her supposed apathetic attitude toward her fans during meet-and-greet events, was again included as one of the Top 50 Japanese Buzzwords for the year.

On October 3, 2016, during a promotional appearance for the brand Baitoru, Shimazaki announced her graduation from AKB48. For the group’s 46th single “High Tension”, released on November 16, 2016, Shimazaki served as the choreographic center in her final appearance on an AKB48 single. She attended the 67th NHK Kōhaku Uta Gassen and graduated from AKB48 on December 31, 2016. Since graduating from AKB48, Shimazaki has pursued an acting career, playing a supporting role in the 96th NHK asadora Hiyokko, appearing alongside veteran actor Kōji Yakusho in a series of television commercials for the national Jumbo Lottery, and playing the role of Marika Tachibana in Nisekoi, the 2018 film adaptation of the manga by Naoshi Komi.

On her 26th birthday on March 30, 2020, Shimazaki launched her official YouTube channel, called Paruroom (ぱるるーむ). It releases a new video every day at 7:00 PM JST. The channel reached 100,000 subscribers on May 2 and has featured other former AKB48 members such as Mariya Nagao and Tomomi Itano. The channel’s opening jingle was created by singer-songwriter Hana Tsuruuchi.