Subsequently, Engonga signed with RCD Mallorca under Héctor Cúper's supervision, along with five other former teammates including Iván Campo. He displayed his best football at the Balearic Islands side, helping them win the 1998 Spanish Supercup after beating FC Barcelona 3–1 on aggregate. Also that year, they reached the final of the UEFA Cup Winners' Cup, losing 1–2 to S.S. Lazio.