[10] Level was established by IAG in response to increased competition in the low-cost long-haul market, including that of Norwegian Long Haul.

On 15 March 2017, IAG CEO Willie Walsh announced the new brand, together with four destinations launching in June 2017 from Barcelona–El Prat Airport (later renamed after Josep Tarradellas in 2019).

Walsh stated the corporation due to take over operation of the brand sold 52,000 seats within two days of being established, and over 147,000 after one and a half months, far exceeding IAG's expectations.

[14] Rome, Paris, and Milan were also mentioned as possible locations for future expansion of the airline in Europe, together with additional routes out of Barcelona.

[22] The COVID-19 pandemic and its associated impacts on aviation resulted in the grounding of Level's short- and long-haul fleet, and the subsequent suspension of its operations starting in March 2020.

[11] As travel restrictions between countries continued to be lifted, Level launched a new route between its Barcelona base and Cancún International Airport on 2 July 2021.

[25][26] On 19 September 2023, Level announced plans to increase its fleet to six aircraft, and with it, a new service between Barcelona and Miami International Airport to begin on 31 March 2024.

[27] On 29 June 2018, IAG announced the launch of a new low-cost Austrian subsidiary, Anisec Luftfahrt, to operate flights from Vienna International Airport, branded as Level, starting from 17 July 2018.

The new subsidiary had its own Austrian AOC and based four Airbus A321 aircraft previously used by Air Berlin and Niki in Vienna, from which it planned to serve 14 European destinations on behalf of Level by the end of August 2018.

[29] On 14 March 2019, IAG confirmed plans to open a second base at Amsterdam Airport Schiphol, with seven routes already operated by Vueling transferred from 6 April 2019 to 15 August 2019.

[35] Level has a registered office in Madrid, Spain, using space shared with Spanish airline Iberia, which is located on the grounds of Adolfo Suárez Madrid–Barajas Airport.

[2] The brand has additional offices on the grounds of Josep Tarradellas Barcelona–El Prat Airport, shared with Spanish low-cost airline Vueling.

[37] Hodder was later succeeded as CEO by Fernando Candela on 9 September 2019, who had previous experience at Spanish airlines Iberia Express and Air Nostrum.