Their third single, "Next Level", was released in May 2021 to widespread commercial and critical success, peaking at number two on the Circle Digital Chart and earning the Daesang[a] for Song of the Year at the 19th Korean Music Awards.

[6] Karina also appeared alongside labelmate Kai for a performance in Hyundai and SM Entertainment's collaboration virtual showcase — The All-New Tucson, Beyond DRIVE.

[9][10] The group's name and members were revealed individually starting on October 27 (in order: Winter, Karina, Ningning, and Giselle).

[11] SM Entertainment founder Lee Soo-man explained the group's concept at the 2020 World Cultural Industry Forum on October 28.

[18] Aespa's version of the song, a "mid-tempo ballad characterized by acoustic guitar sound" with "warm lyrics about promising forever to a loved one",[19] was released on February 5.

[20] On May 4, SM Entertainment announced Aespa would release a new single titled "Next Level", a dance and hip-hop track with a "groovy" rap, "energetic" bass, and "powerful vocals".

[26] On July 22, it was announced that Aespa had signed with Creative Artists Agency for their future activities in the United States.

[30] It was released on October 5 to critical acclaim and commercial success, with media outlets praising "Savage" for its "addictive" hooks, refrains, and "masterfully layered" production.

[35] On October 15, ten days after release, at 1:30 p.m. KST, Instiz's iChart, announced Aespa's first perfect all-kill, as "Savage" had reached number one on the real-time, daily, and weekly components of the domestic charts — iChart, Melon, Genie, FLO, Bugs!, and Vibe — becoming the first "fourth generation" K-pop act to do so.

[37][38] Savage has sold a total of 788,959 copies and held the record for the highest-selling debut album by an SM Entertainment act, until it was surpassed by NCT DoJaeJung's Perfume in May 2023.

Their setlist included "Savage", "Next Level", "Black Mamba", and an English version of a then-unreleased song titled "Life's Too Short", which was revealed to be from their then-upcoming EP.

The magazine noted Aespa as an "experimental but essential player in the music industry, acting as a bridge between the reality and virtual".

[62] It went on to debut at number one on the Circle Album Chart with 1,426,487 copies sold, leading to their first Million certification by the Korea Music Content Association.

Throughout the show, the members were tasked to find hidden 'ae-key' cards, won from various missions and games, in order to 'complete' the eponymous Synk Road.

[78] From March to April, Aespa continued their Synk: Hyper Line concert tour in Japan, garnering a total of 110,000 spectators from 10 sold-out shows across Osaka, Tokyo, Saitama, and Aichi.

Billboard 200 chart, My World debuted at number nine with 40,000 album-equivalent units, 1.33 million on-demand streams and 39,000 pure album sales, becoming their second top 10 entry.

[86] On May 10, SM Entertainment announced that Aespa's Synk: Hyper Line tour would continue with a show in Jakarta, Indonesia on June 24.

[94][95] On July 27, Aespa began teasing their English digital single "Better Things", a "minimal up-tempo dance" song, which was released on August 18.

Aespa first performed the single on August 13, at the Crypto.com Arena in Los Angeles, for the first show in the US leg of their Synk: Hyper Line tour.

The single served as the inaugural opening theme song for the Korean edition of the Pokémon: Liko and Roy's Departure anime, which began airing on the same day.

[100] On January 9, 2024, SM announced that Aespa would be releasing a remake of "Regret of the Times", a single originally by Seo Taiji and Boys.

[101] On February 19, it was announced that Aespa would be embarking on their second world tour, Synk: Parallel Line, kicking off in Seoul on June 29 and 30.

[103] "Supernova" was a commercial success in South Korea and achieved perfect all-kill status, as it simultaneously reached number one on the real-time, daily, and weekly components of iChart.

[107] Later on June 29 and 30, when kicking off their second world tour at Jamsil Indoor Stadium, Aespa revealed four solo tracks, one from each member.

[110] On September 23, it was announced that Aespa would be releasing their fifth extended play Whiplash on October 21, containing six tracks including the lead single of the same name.

[120] In August, Aespa became the global ambassador for the Korean sportswear brand MLB,[121] selected as new model for Lotte Duty Free.

[122] On September 1, Aespa became the global ambassador for Swiss watch and jewelry brand Chopard,[123] and was featured in advertisement for Intel.

[127] On February 28, South Korean cosmetics company Amorepacific selected Aespa as their new global ambassador for Mise-en-scène.

[128] In May, Aespa has been appointed as Incheon International Airport's honorary ambassador,[129] and became the model for the new brand Refrear Series contact lens "a-eye".