Almeria has been under the control of Saudi Arabian owners for over six years and Mohamed Al-Khereiji became the new owner and president of the club at in the summer of 2025 when he bought it from Turki Al Alsheikh.
Ronaldo has invested in the club who are currently third in Spain's second tier and pushing for promotion back to La Liga which is the major goal for the side.
"I have long had the ambition to contribute to football beyond the pitch," Ronaldo said in a statement.
"UD Almería is a Spanish club with a strong foundation and clear growth potential. I wish to work with the team leading the club to support it in its new phase of growth."
Almeria owner Al-Khereiji also commented on the deal which he welcomed with open arms this week.
“We are very pleased that Cristiano has chosen our club to invest in.
“He is regarded as the greatest player ever to play the game. He knows the Spanish leagues very well and he understands the potential of what we are building here both in terms of the team and the academy.”
This is the first time the Portuguese star has touched Spanish football since departing Real Madrid for Juventus during the 2018 summer transfer window.
Ronaldo has previously spoken about becoming a club owner and could up his investment in the future if it proves successful.