Before taking his post at the European Investment Bank, Niinistö served as a Member of the Finnish Parliament, Minister of Finance, and as chairman of the National Coalition Party.
Niinistö's decision was announced by Party Chairman Jyrki Katainen on Thursday. Niinistö said that his main aim was to defend the Finnish way of life, and keep it strong in the future.
He added that he believes that Finland's international success is rooted in Finnish tradition, attitudes and values.
Niinistö refused to run for President in the previous elections in 2000, saying at the time that he wanted to focus on his family life, and on projects linked with state finances.
Meanwhile, the candidacy configuration for the elections appears to be taking shape. On Thursday President Tarja Halonen indicated that she might make an announcement on whether or not to seek a second term alreay in May.
Social Democratic Party Secretary Eero Heinäluoma said on Thursday that Sauli Niinistö's early announcement will not affect his party's plans.
Prime Minister and Centre Party Chairman Matti Vanhanen is expected to make his announcement on April 23.
According to a poll published Thursday, President Halonen still enjoys an unassailable lead. Fifty-five percent of those polled said they would vote for her, which would place her straight back into the Presidential Palace after the first round of voting.
Niinistö's support has grown from 13 percent to 15 percent since January. Prime Minister Matti Vanhanen has also been touted as a possible candidate for the Centre Party. His support stood at 18 percent, a drop from the previous 23 percent.
Over 1,400 Finns took part in the study.
