"I wish for the holy spirits and His Majesty the King's graciousness to give happiness to all Thais and I hope the Thai people and their country will see good things and overcome all obstacles in the end," Ms Yingluck told reporters after giving food offerings to 109 monks.
Ms Yingluck and her 11-year-old son Supasek Amornchat then joined a Songkran procession which began in Chiang Mai's Muang district.
At an anti-government rally site in Bangkok's Lumpini Park, protest leader Suthep Thaugsuban and his supporters conducted a merit making ceremony and gave food offerings to monks on the occasion of the Thai new year.
Mr Suthep said the People's Democratic Reform Committee (PDRC) will organise Songkran activities from Sunday to Tuesday.
He said Songkran revellers are not allowed to bring in their own water, powder or water guns into the Lumpini site for security reasons. The PDRC will provide them with water and other equipment, he added.