The First Minister was part of a remoaner mission to the Belgian capital, joined by Jeremy Corbyn and Labour’s Welsh first minister Carwyn Jones.
The trio met with EU chief negotiator Michel Barnier – who previously stated he would not negotiate with Scotland behind Britain’s back.
Ms Sturgeon was expected beg the Frenchman to help her prevent an “extreme Brexit outside the Single Market” during a 45-minute meeting after her attempts to disrupt leaving the EU with an opportunistic independence referendum backfired.
Independence “obsessed” Sturgeon was seen leaving after just 45 minutes.
She is expected to speak in Glasgow upon her arrival to the airport.
Meanwhile, Mr Corbyn was on his mission as he admitted he went to tell Mr Barnier he is “ready to take up the responsibility for Brexit negotiations” over Theresa May.
A spokesman for Ms Sturgeon said the meeting designed to ensure Scotland gets a good deal.
He said: “This is an opportunity to brief Mr Barnier on Scotland’s priorities and seek to enhance our understanding of the current EU position as Brexit negotiations continue.
“Our priority is protecting Scotland’s vital interests and building consensus against an extreme Brexit outside the single market, which would be potentially disastrous for jobs, investment and living standards.
“This is not about holding separate Scottish negotiations – we have always accepted that the EU will only negotiate with UK, which is why we will continue to work hard to influence the UK position.”
Mr Corbyn’s meeting came directly after Barnier’s talks with Nicola Sturgeon.
Mr Jones said he would push for “full and unfettered access to the Single Market” after Brexit.
Arriving for the talks, Mr Corbyn said he was representing 13 million people who voted Labour at last month’s election.
“These are crucial negotiations for our country,” said Mr Corbyn.
“We are here to ensure that we protect jobs and living standards and to try to discover exactly what the views of the EU are on the whole process.”