Pichette replaces Omid Kordestani, who stepped down as executive chairman Monday, but who will remain on the board as a non-employee director.
Pichette has been lead independent director since Dec. 31, 2018.
“We believe that now is the right time to evolve our governance structure in-line with best practices,” Pichette said in a statement. “We are pleased to demonstrate our commitment to good governance and be in the position to make this important change. We look forward to continuing to benefit from Omid’s expertise on the board,” he said, according to the statement.
Kordestani said he feels “confident that I can now step back from my active role as executive chair. Patrick has been an important, independent voice in the board room and is the right person to assume this new role as independent chair,” according to the statement.
The shift in governance comes at Twitter is engaged in a growing conflict with President Donald Trump over his use of the social media platform to spread misinformation, lies and conspiracy theories.
Last week Twitter attached a fast-checking warning label to two Trump tweets about mail-in voting with links to credible information on the practice.
Trump responded by tweeting outrage and signing a largely symbolic executive order urging the FCC to review a section of the Communications Decency Act that protects tech companies from liability for material posted on their sites and platforms.
Twitter shares were little changed in after-hours trading.