He said he is convinced enough to heed the calls made by Nigerians for him to contest.
The former minister of education is believed to have first written a letter of intent to the PDP in 2017, but it was made public on Monday, April 30, 2018.
In the letter, he claimed that the successes of his previous years as governor and minister appear to have convinced Nigerians that he is fit to fill the role of president.
He also disclosed that he has consulted widely across the country and is convinced enough to heed the calls made by Nigerians for him to contest.
The letter read, "As you may be aware, for quite some time now, since after the 2015 general elections, there have been various calls made by individuals and groups from many quarters, nationwide, urging my humble candidature for the contest of the presidency of the Federal Republic of Nigeria in the next general elections, due in 2019.
"I strongly believe that the people are doing so out of their conviction of contentment and satisfaction based upon the modest successes recorded while I served as the Governor of Kano State (2003 to 2011), and also as a Minister of Education (July 2014 - May 2015).
"In response to these calls, and in view of the seeming intricacies and the boundless complexities involved in such a national assignment, I have consulted across the geopolitical zones and different interest groups, who examined and appraised the issue and advised me accordingly.
"I am pleased to say, based on these wide consultations, that I am better informed and convinced that participating in the democratic process of serving humanity goes beyond party affiliations/boundaries, and also beyond just winning an election.
"I have therefore decided to accept the clarion calls, and will in due course and in accordance with the guidelines of my party, the People's Democratic Party (PDP), offer my humble self for the contest of the presidency of the Federal Republic of Nigeria during the forthcoming 2019 general elections."
With his declaration, Shekarau will have to beat former vice president, Atiku Abubakar, to the primary ticket of the PDP. Atiku is considered the favourite and expected to be President Muhammdu Buhari's biggest challenger in the 2019 presidential election.