"I strongly encourage the United States to give Ukraine a special security and defense status which reflects the highest level of interaction with non-NATO allies," Poroshenko said in an emotional speech to the House of Representatives and Senate.
He was interrupted frequently by applause and standing ovations.
Poroshenko asked for more aid for Ukraine's military, going beyond equipment such as night-vision goggles that Washington has already sent.
"They need more political support throughout the world. They need more military equipment, both lethal and non-lethal," he said.
"Blankets, night-vision goggles are also important, but one cannot win the war with blankets," he said.
Poroshenko also pushed for more sanctions against Russia for its seizure of Crimea from Ukraine and backing of the separatist movement.
"I also asked that the United States be forceful and reflect its principles with the respect of further sanctions against the aggressor," Poroshenko said.
As Poroshenko visited the U.S. Capitol, President Barack Obama's administration pledged $53 million in fresh aid to Ukraine for its struggle against Russia's incursion, including counter-mortar radar equipment.
