The Amazon founder kept it casual for the Monday visit, wearing fitted blue jeans and a white T-shirt. Bezos was joined by girlfriend Lauren Sanchez and Hollywood producer Shep Gordon.
Meanwhile, Musk seemingly dissed Bezos' Washington Post after the outlet published a business analysis titled, "Elon Musk's Twitter Investment Could Be Bad News for Free Speech."
"Ouch, I just snorted coffee out of my nose," tech entrepreneur Marc Andreessen wrote on Twitter, including a snapshot of The Washington Post headline.
"WaPo always good for a laugh," Musk responded.
The Tesla CEO purchased a 9.2% stake in Twitter Inc. according to a Monday filing to the SEC.
Twitter's shares jumped more than 25% following Monday's news. Musk now controls nearly 73.5 million shares of the company, making him the largest shareholder. Individual stocks were priced at $49.81 on Monday morning.
Twitter board members seemingly welcomed Musk over social media.
Twitter CEO Parag Agrawal led the way in announcing Musk's appointment, saying that "he's both a passionate believer and intense critic of the service which is exactly what we need on @Twitter, and in the boardroom, to make us stronger in the long-term."
Independent Twitter board chair and Salesforce co-CEO Bret Taylor followed, writing, "We are all excited to work with you and build the future of Twitter together."
Twitter co-founder and former CEO Jack Dorsey also extended gracious remarks, tweeting, "I’m really happy Elon is joining the Twitter board! He cares deeply about our world and Twitter’s role in it. Parag and Elon both lead with their hearts, and they will be an incredible team."
Fox Business' Anders Hagstrom and Breck Dumas contributed to this report.