The agreement came at a one-day EU/Ukraine summit on Thursday where Brussels said it wanted to maintain Ukraine as "an important transit country" for its energy supplies.
The EU also used the meeting to reaffirm its "unwavering support for Ukraine's independence, sovereignty and territorial integrity."
Ukrainian President Petro Poroshenko met Commission President Jean-Claude Juncker and his Council and Parliament counterparts, Donald Tusk and Martin Schulz.
The two sides also confirmed several "support programmes" on decentralisation, the fight against corruption, public administration reform and the rule of law.
All are part of a package totalling €300m.
It was also agreed that the EU will provide €6m for community policing and public order and an additional €5m to the OSCE special monitoring mission, for which it has already provided €25m.
The EU representatives also underlined their "commitment" to grant visa-free travel for short stays in the Schengen area to Ukrainians.
Additionally, a new memorandum of understanding (MoU) on a strategic energy partnership between the EU and Ukraine was signed at the summit.
This replaces the previous agreement on energy cooperation, which was signed in 2005.
A Commission source said, "The new MoU foresees enhanced cooperation on a number of energy topics, from energy security to full market integration and from energy efficiency and decarbonisation of the economy to research cooperation."
Speaking after the summit, European energy union Commissioner Maros Šefčovič said, "Ukraine has been a long-standing strategic energy partner for the EU. It has been a reliable transit country for transporting Russian gas to EU countries even during recent turbulent times."
He added, "We want to maintain Ukraine as an important transit country also for the future. Ukraine fully supports the Energy Union and wants to be a strategic partner in its implementation.
"It is now time to expand our energy cooperation and attract more investment in all other areas of energy, including renewables and energy efficiency."
Further comment came from Donald Tusk, who praised Ukraine's efforts to implement internal reforms, saying, "The last three years have seen the birth of a new Ukraine that advances its democracy and economy through, sometimes very tough, reforms. Additional assistance from Europe should support Ukraine in strengthening its democratic path."
Juncker said, "Over the last two or three years, while working faithfully with Poroshenko and his government, we have witnessed a great deal more progress during this short period than in the previous twenty years."
Poroshenko, speaking later at a news conference, said he does not believe the administration of US President-elect Donald Trump will change Washington's backing for the country.
He said Trump had raised with him Russian "aggression" against Ukraine and its "illegal" annexation of Crimea.