Formed at Celta, where he played mainly in the reserves, he achieved totals of over 175 La Liga games and 50 goals for that team, Espanyol and Betis, winning the 2021–22 Copa del Rey with the latter.

[9] Additionally, he scored braces against Córdoba CF, Sevilla Atlético, Real Valladolid and CA Osasuna, to reach 15 goals by March[10] and finish the season as the division's joint-third highest scorer on 22.

[15] Iglesias scored three goals over two legs in an aggregate 7–1 win over Ungmennafélagið Stjarnan in the second qualifying round of the UEFA Europa League in late July and early August 2019.

[17] He struggled with just three goals as the team finished 15th in his debut campaign,[18] and received a red card on 20 February at the end of a goalless draw at CD Leganés for pushing an opposition coach.

[20] In the decisive match on 23 April, he scored the opening goal of a 1–1 draw with Valencia as his team won on penalties;[21] he also topped the tournament's individual charts at five,[22] and was the final's most valuable player.

[25] On 6 November, both he and teammate Nabil Fekir (as well as Gonzalo Montiel for the opposition) received straight red cards in an eventual 1–1 home draw with Sevilla in the Seville derby.

[27][28] On 27 January 2024, he was sent on loan to Bundesliga club Bayer 04 Leverkusen until the end of the campaign, with a reported option to buy for €8 million;[29] he arrived to cover for the injured Victor Boniface.