A number of contestants (known as "housemates") lived in a purpose-built house in Espoo, and were isolated from the rest of the world.

After receiving 43,8% of all votes, Kaarlo became eligible to win the prize money and re-entered the house on Day 91.

In the 2005 season of Big Brother Suomi, viewers could only vote to evict the nominated housemates they wanted to leave the house.

On September 26, Mika was removed from the house for the alleged attempt to sexually abuse a fellow female housemate, Sorella.

Big Brother stopped Mika by ordering him to come to the Diary Room, and later, the incident had undergone police investigation.