Detectives are also hunting a number of other suspects who took her phone and other belongings while she was being sexually attacked.
The shocking incident happened in the Costa Blanca town of Torrevieja.
Officers have not specified the date of the rape but said it happened about 6am.
The 27-year-old Moroccan accused of the vicious sex attack has been remanded in custody while police continue to try to track down the other suspects, believed to be accomplice friends of his.
A spokesman for the Guardia Civil in the Costa Blanca capital of Alicante confirmed: “The Civil Guard has arrested a 27-year-old Moroccan man in Torrevieja as the suspected author of a sex attack on a Belgian woman aged 32.
“Officers are still hunting several people who took advantage of the situation to rob the victim.
“She was out walking her dog, about six in the morning, when she was approached by a man who began to speak to her in several different languages.
“The woman was on holiday in the area and when she couldn’t understand what he was saying continued on her way.
“The man however grabbed her by the arm and attacked her sexually, with penetration taking place.
“During the struggle other people appeared on the scene and took advantage of the situation to steal her mobile and several other belongings while she was in a state of total helplessness.”
Police held the suspect after a surveillance operation outside local nightspots where he was thought to have spent time before the attack.
They found a “unique” hat the victim had described him as wearing when they got a court order to search his flat, as well as several items of clothing which coincided with the ones she told officers he had on.
The police spokesman added: “The operation continues to track down and arrest the people who stole the victim’s belongings while she was being sexually attacked.”
The suspected rapist was remanded in prison following a court hearing in Torrevieja held behind closed doors.