On 3 July 2013, Peña signed a two-year contract with Segunda División club CD Lugo.[5] He made his league debut on 17 August, playing 65 minutes in a 0–0 home draw against CD Numancia,[6] and scored his first goal as a professional on 19 October by netting his team's second in a 3–3 draw at Recreativo de Huelva.[7]
Peña joined Racing de Santander of division three in August 2015, on a two-year deal.[8] On 5 July 2017, he returned to the second tier after agreeing to a two-year contract at AD Alcorcón.[9]
On 17 January 2019, Peña signed a two-and-a-half-year contract with Albacete Balompié, still in the second division.[10] On 2 September, he moved to CD Mirandés of the same league on loan for the season.[11]
On 25 August 2022, Peña signed a one-year contract (with an option to extend) with Almere City FC in the Dutch Eerste Divisie.[14] He won promotion to the Eredivisie in his debut campaign via the play-offs, a first-ever for the club in its 22-year history to which he contributed five goals from 31 appearances.[15]
Peña scored his only goal in the Dutch top tier on 17 December 2023, in a 5–0 home victory over SBV Vitesse.[16] His side managed to easily avoid relegation, finishing with 34 points.[17]
On 17 July 2024, Peña joined FC Andorra on a one-year deal with an option to extend.[18]
^Del Campo, José Luis (3 July 2013). "Lugo: Álvaro Peña, dos años con los gallegos" [Lugo: Álvaro Peña, two years with the Galicians] (in Spanish). Todo Mercado Web. Retrieved 11 July 2013.
^Ruiz, Pako (30 June 2023). "Álvaro Peña: "Disfruto como un niño"" [Álvaro Peña: "I'm happy as a kid"] (in Spanish). Onda Vasca. Retrieved 7 September 2023.