Modi was received at South block office of the PMO by newly appointed Principal Secretary Nripendra Mishra and some other officials.
As soon as he entered his office, he paid obeisance to the Father of the Nation Mahatma Gandhi by offering flower tributes to his photograph.
However, even before assuming charge, Modi had already began his official work last night itself by holding a meeting with top officials.
Soon after he was sworn-in as Prime Minister, Modi sought support, blessings and active participation of the people to take India's development journey to newer heights.
"Together we will script a glorious future for India," he said in his first message on the relaunched PMO website.
"Let us together dream of a strong, developed and inclusive India that actively engages with the global community to strengthen the cause of world peace and development," he added.