Madeleine was three years old when she disappeared whilst on holiday with her Catholic parents in the Algarve resort of Praia da Luz on May 3, 2007.
The service will take place at the Church of Nossa Senhora da Luz at 9pm, which is the same time that Madeleine vanished.
It will be led by Father Haynes Hubbard, of Canada, the former priest of the church at the time of Maddie's disappearance. He has over the years become a close family friend to her parents Kate and Gerry.
A public gathering is also expected to take place in her home village in Rothley, Leicestershire, to mark today's anniversary.
In previous years, the anniversary has been remembered by members of the McCann family and villagers near their local war memorial.
Paul Luckman, a Christian and the publisher of the Portugal News told Premier interest in the case there is nowhere near the level of the UK.
"There are no ribbons, there are no posters, there's nothing. The reality is that everyone really has moved on. That's hard but that's the reality.
Luckman said it's "unlikely" many locals would attend tonight's service.
Madeleine's parents have vowed to do "whatever it takes for as long as it takes" to find their daughter, who would now be nearly 14.
Speaking ahead of the anniversary, the couple described it as a "horrible marker of time, stolen time".
Mrs McCann said: "I think we'll get by as we have any other year really, we'll be surrounded by family and friends, you know, obviously we'll be there remembering Madeleine, as we always have."
Last month, Scotland Yard said its officers are still pursuing "critical" leads to trace Madeleine, with officers receiving information on a daily basis.
Click here to listen to Paul Luckman speaking with Premier's Eno Adeogun: