Julian King, currently UK ambassador to France, was offered a job focused on counter-terrorism, a new brief created after Jonathan Hill resigned from the EU's executive arm last month following Britain's vote to leave the EU.
MEPs have been swift to respond, with S&D group leader Gianni Pittella saying, "Security is a vital topic for the EU and it is good that we will now have someone working specifically on coordinating the European agenda on security."
The Italian deputy added, "This is something European citizens have called for and something we fully support.
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"It is important that this work is done in support of home affairs Commissioner Dimitris Avramopoulos, and under the direction of first Vice-President Frans Timmermans. The approach of leading a task force of experts from existing departments and providing advice is the correct one.
"Before the appointment, we made clear to European Commission President Jean-Claude Juncker that Julian King's role should not take away responsibility from any Commissioners from the Socialist family. We are pleased that this is the case.
"We now need to look at the exact details of what the role will entail but we are pleased that security and migration policy are kept separate, something our group has insisted on for a long time."
UK Conservative MEP Anthea McIntyre also welcomed the allocation of the new security brief to King, saying it showed that Juncker "acknowledged the UK's continuing lead role in security issues."
Juncker moved carefully to fill the spot in the college, even though Britain voted to leave the EU over the next few years.
King's new job will be subordinated to more high-profile posts, entailing coordination efforts to fight terrorism by tracking returning fighters from the Middle East, boosting intelligence sharing among member states and stemming radicalisation.
McIntyre, an ECR group deputy, said: "We face a global threat in terrorism and organised crime. The creation of this new Commission role and Sir Julian's appointment to it speaks volumes. It highlights Britain's expertise and clout.
"This leading contribution on security matters will continue to be important post-Brexit, not just across Europe but across the world.
"The director of Europol, Rob Wainwright, is British and Royal Navy officers are in command of the EU's anti-piracy patrols which have been so successful off the Horn of Africa.
"Sir Julian's himself has held senior posts at the UN Security Council, Nato and the EU's Political and Security Committee.
"I hope continued cooperation on security will be at the heart of the Brexit negotiation."
UK Prime Minister Theresa May's office welcomed Juncker's assignment, saying that Britain will remain an "active player" in EU affairs. "The UK will continue to fulfill our rights and obligations as a member state until we leave the EU," a spokesperson for the premier said in a statement.
King still has to be confirmed in the post at a hearing in Parliament in September.