"Elon has decided not to join our board. I sent a brief note to the company, sharing with you all here," the Twitter CEO posted, sharing his note.
Agrawal said the company had many discussions with Elon Musk over joining the board.
"Elon's appointment to the board was to become officially effective 4/9, but Elon shared that same morning he will no longer be joining the board. I believe this is for the best," he wrote.
"We were excited to collaborate and clear about the risks. We also believed that Elon as a fiduciary of the company where he, like all board members, has to act in the best interest of the company and all our shareholders, was the best path forward. The board offered him a seat."
Musk's appointment to the board was to become effective on April 9, Saturday, but he informed that morning that he will no longer be joining the board, Agrawal said in his post.
"I believe this is for the best. We have and will always value input from our shareholders whether they are on our board or not. Elon is our biggest shareholder and we will remain open to his input," the Twitter CEO said.
He added that there will be "distractions ahead but our goals and priorities remain unchanged". "The decisions we make and how we execute is in our hands, no one else's. Let's tune out the noise, and stay focused on the work and what we're building," Mr Agrawal added.