Mallorca and Atletico Madrid have been negotiating since the start of the week, and the 19-year-old forward will now become part of the Rojiblanco reserve side, as first reported by Radio Marca Baleares.
The move is structured as a loan with a purchase option, and Domenech is set to travel to Madrid in the coming hours to complete his medical.
The forward, from Llucmajor, enjoyed a rapid rise from Mallorca's youth ranks through to the first team, though a loan spell at Ceuta last season proved difficult, cut short by injuries and a lack of continuity. He will now look to rebuild his form under Fernando Torres in the Primera RFEF, Spain's third tier, where Atletico's reserve side compete.
The player Domenech is being asked to replace in some respects is Arnau Ortiz, who scored 23 goals for Atletico Madrileño last season before earning a step up to Diego Simeone's first-team squad.
Ortiz made his LaLiga debut as a starter in Atletico's league opener against Malaga, a path Domenech will hope to follow if he impresses at his new club. Domenech, who signed a contract extension with Mallorca until 2029 last year, arrives with experience across three senior categories of Spanish football, including 17 appearances in the top flight and time in the second tier with Ceuta.
The forward primarily operates as a central striker but is also comfortable on either wing, with his finishing, movement into space and reading of defensive gaps considered his strongest attributes.
Whether Domenech ultimately becomes part of Simeone's plans or continues his development with the reserve side will depend on how he performs once he settles into life in Madrid.