The Equatorial Guinea international received the maximum punishment available under Article 102 of the RFEF Disciplinary Code, with the committee also imposing the associated financial penalties under Article 52.
The incident occurred during the Segunda División fixture between Tenerife and Andorra on November 2. Owono was sent off after challenging De Miguel with his leg raised while the two players contested the ball.
The Tenerife forward required emergency medical attention on the pitch and was taken to hospital, where he died the following day.
In its ruling, the disciplinary committee said its assessment had to be based on the facts recorded in the referee's report.
"The assessment of the conduct under consideration in these proceedings must be based on the facts expressly recorded in the referee's report, which states that the player was sent off for striking an opponent forcefully with his leg raised, using excessive force while the ball was in play," the committee stated.
It considered the nature of the challenge, the force involved and the consequences when deciding to impose the maximum suspension.
"The referee's own description makes it possible to appreciate the particular seriousness of the action, both because of the way it was carried out, with the leg raised, and because of the forcefulness of the impact, which the referee expressly described as excessive."
The committee also referred directly to the death of De Miguel when explaining its decision.
"It is public knowledge that the tragic outcome of the events was the death of Jesús de Miguel Alameda," the ruling stated, concluding that the circumstances justified the maximum 12-match punishment.
The decision brings an end to the uncertainty surrounding the sporting sanction after the federation had delayed its ruling because of the exceptional nature of the incident.
Owono has also been dealing with the emotional consequences of what happened. He withdrew from Equatorial Guinea's squad for their Africa Cup of Nations qualifying matches against Zimbabwe, while Andorra coach Carles Manso said the club would give the goalkeeper the time and space he needed before deciding when to return to competition.
Owono had previously described the period as the most difficult days of his life, expressing his pain over De Miguel's death and his thoughts for the striker's family.
The 12-match suspension is a disciplinary decision under the RFEF's football regulations. It should be distinguished from any separate investigation into the circumstances of the collision.
The tragedy has had a profound impact on both clubs and Spanish football, with the disciplinary committee's ruling now confirming the maximum sporting punishment available under the provision applied to the challenge.