On Tuesday, the Facebook CEO appeared before European lawmakers following months of scandals that have beset the social network - from the spread of fake news to Cambridge Analytica's misappropriate of up to 87 million users' data.
Just over a month after giving an apology for his company's recent mistakes during two grueling days of USA congressional hearings, Zuckerberg has had rather less time to respond to members of the European Parliament who demanded answers - and contrition - after 2.7 million European Facebook users were compromised by political data firm Cambridge Analytica.
"Whether it's fake news, foreign interference in elections or developers' misusing people's information, we didn't take a broad enough view of our responsibilities", Zuckerberg said at the hearing.
Zuckerberg agreed that Facebook had been "too slow" to identify that there was Russian interference in the 2016 USA presidential elections. I asked you six yes or no questions and got not a single answer. To which Zuckerberg responded with a slightly dismissive, "I'll make sure we follow up and get you answers".
Zuckerberg said investments in security would significantly impact Facebook's profitability, but "keeping people safe will always be more important than doubling our profits".
Crucially, Zuckerberg also voiced support for a major piece of European legislation set to come into place this Friday, called the General Data Protection Regulation.
The Facebook CEO used his short answer period to explain that he feels like there's plenty of new competition for Facebook, and that it actually aids competition by offering tools to enable small businesses to challenge big brands online.
"Will you promise there will no cross-use of user data between Facebook and WhatsApp?". Zuckerberg was given time to answer them in the end.
Several of the politicians expressed frustration at this, and one accused Mr Zuckerberg of having "asked for this format for a reason". Since no one stopped him, he said he wanted to "be sensitive to time" and ignored questions that some of the more insistent politicians kept repeating, like whether Facebook would allow users to avoid targeted advertising.
However, he only agreed for it to be livestreamed on Monday after initially insisting on it being behind closed doors.
And yet, just minutes after the meeting ended, Tajani faced criticism about the format he had negotiated, which many said did not allow for proper scrutiny of the chief executive responsible for a privacy breach that affected millions of Europeans.
While most questions focused on how Facebook cares for users' data, Manfred Weber, the leader of the centre-right EPP group, and Guy Verhofstadt, a Liberal former Belgian prime minister, raised a potentially chilling point for Zuckerberg - should it be split up?
Complying with European Union data law: Facebook "expects to be fully compliant" when the law comes into effect on Friday. Some EU lawmakers asked how Zuckerberg views the competitive landscape, questioning whether it's a monopoly and if it needs breaking up.
As was the case when he appeared before Congress, Zuckerberg largely avoided answering questions about Facebook's data collection practices, including the data it gathers from non-users.
Data privacy is a major issue among European citizens.
She added: "I would like you to tell us what you are doing to stop the rise of false Facebook accounts which deliberately target young and vulnerable people?"
Zuckerberg said Facebook's artificial intelligence systems flag 99% of content linked to al Qaeda and the Islamic State of Iraq and Syria (ISIS), which is removed before anyone in the community reports it. Facebook also has hired 3,000 people to quickly respond to people who pose a harm to themselves.