Humud Alghudaini, Mobily's spokesman, said on Monday: "The decision was taken last night because of a fatwa [religious decree] issued last year, since the programme is culturally inappropriate.
"It shows men and women living in one house, sometimes semi-naked and in inappropriate situations."
The programme entered its third season last week with two 21-year-old Saudi men among the 19 contestants from around the Arab world who will share a house 24 hours a day in an attempt to win a recording contract.
Saudi Arabia, home to the puritan Wahhabi school of Islam, requires women to be fully covered and accompanied by a male relative in public. Mixing of unmarried men and women is forbidden.
Saudi Telecommunications Co (STC), the main mobile firm in the conservative kingdom, said last January that it would block customers from voting by text message.
STC has about 10 million subscribers, compared with the two million of new-comer Mobily, which is owned by Etisalat, a telco in the United Arab Emirates.
Alghudaini said: "We will definitely lose money, but how much, I don't know. If we don't [stop messages] it would backfire on us and affect our brand."
April's victory by Hisham Abd al-Rahman triggered the closest thing to pop hysteria in ultra-conservative Saudi Arabia, as admirers rushed to shake his hand or even kiss him at an appearance in a shopping mall in Riyadh.