Firstly, she will update leaders for the third time on the work she has been leading on the external challenges of migration, in particular the work the EU has been doing on external partnerships, especially with partner countries in Africa.
Secondly, she will report on the ongoing work on defence and security, where a number of important decisions have been taken over recent weeks unanimously by all 28 EU Member States.
"Just a few days ago here in Brussels with all the Foreign and Defence Ministers, we have decided to launch a military capability on planning and conducting our military missions - a joint one of the European Union," the High Representative said as she arrived at the Summit.
"And I would expect the Council today to recognise the work done and encourage us to go further especially on Permanent Structured Cooperation on defence in the months ahead."
Mogherini will also report back on her visit last week to all six Western Balkan countries.
"I would expect that the European Council will today send a very strong message of engagement, commitment, openness and credibility of the path that will lead the region towards the European Union integration."