'You are the true heroes,' Ronaldo tells Syrian children
The Portuguese player also donated a "generous" sum to charity Save the Children to provide life-saving relief to children and families in the war-ravaged country.
Ronaldo shared his special message to Syrian children in a video posted on his social media channels.
"This is for the children of Syria," he said. "We know that you have been suffering a lot. I am a very famous player – but you are the true heroes. Don't lose your hope. The world is with you. We care about you. I am with you."
The donation will help Save the Children provide much-needed food, clothing, emergency medical care and psychosocial support to vulnerable children and families who have been living for years under siege and under constant bombardment.
"With our partners in Syria, we have been helping children in Aleppo and are supporting the thousands of families who have now fled their homes," said Nick Finney, the charity's northwest Syria Country Director.
"Our partners are distributing food baskets and emergency supplies, and are providing medical assistance in the areas where people leaving Aleppo are arriving to, often with nothing but the clothes on their backs.
"We run dozens of health centres and schools in the region. After some of the most intense violence and brutal siege we have seen in Syria's conflict, families urgently need our help."
He added: "Cristiano Ronaldo's generous donation will help us to support children from Aleppo and across Syria, who have suffered things children should never have to live through. We are tremendously grateful for his life-changing support.
"Ronaldo is not only one of the world's most iconic sports figures, but he also has become a beacon of hope for millions of boys and girls worldwide – and hope is something that Syria's children need now more than ever."
The Real Madrid forward has been a Save the Children Global Artist Ambassador since 2013 and has been encouraging his fans and more than 250 million social media followers to join him by sharing their own messages of hope to Syrian children on social media, using the hashtag #Syria.
Earlier this month the tragedy in Aleppo captured the world's attention including celebrities, who took to social media to express solidarity with Syrians.