The former Bearsden Academy student gained a seat for the West of Scotland region having first joined the party when he was just 15.
Serving as a member of the Scottish Youth Parliament, he unsuccessfully contested the General Election last year in Dunbartonshire East before earning electoral success as an MSP.
Greer was an active contributor in the campaign to allow 16 and 17-year-olds the chance to vote in the Scottish Independence referendum.
Since the vote, he has worked for the Scottish Greens on strategy development and holds the European and external affairs party spokesman brief.
Whilst he celebrates his victory and the setting of a new record for Scottish politics, Greer has aroused some controversy on social media in the past.
While employed by Yes Scotland during the referendum he made some contentious remarks on his Twitter account.
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In one exchange, he revealed that he tried to stop anybody who he deemed unacceptable, to be affiliated with the Yes campaign from having a connection to it.
Bella Caledonia’s Alistair Davis (@moh_kohn) asked: “Rather an odd thing to do, Ross. Was inhibiting folk you didn’t like in your job description?”
Greer tweeted back: “@moh_kohn folk who would harm the campaign, yes.”
Greer’s online presence will undoubtedly become a regular point of interest following his win last night.
Whilst his personal remarks have been called into question, his posts on the Greens website appears to be more in keeping with the party politics: ‘Only the Scottish Green Party offered the practical solutions that I wanted, combining social justice and equality with sustainability and practical solutions to tackling climate change.’