Exit polls showed that Poroshenko won around 23 per cent of the vote.
Members of the European parliament were present in Ukraine to observe the elections. Andrej Plenković, who is head of the delegation, said that he was "pleased with the general conduct of the elections".
He congratulated "all levels of the country for the efforts which they have invested into organising early parliamentary elections".
Plenković highlighted that the elections took place "in an extremely difficult context whereby Crimea has been illegally annexed by Russia and whereby a number of areas [held by the rebels in the East] were prevented from [voting]".
He added that the "Ukrainian people have clearly chosen Europe as [their] orientation and people have clearly chosen peace". The EPP deputy hoped that "the new parliament will form a stable government and will be constituted swiftly, [so as to] embark on comprehensive Europe oriented reforms".
Looking ahead, he said the European parliament "will accompany the government in implementing the association agreement, [which should be used] as a guiding tool for reforms to be implemented in months to come".
"[The] Ukrainian people have clearly chosen Europe as [their] orientation and people have clearly chosen peace" - Andrej Plenković
Parliament president Martin Schulz was also pleased with the general conduct of the elections in Ukraine, describing them as "fair and pluralist". He added that "Ukrainians can be proud of what they have achieved."
Schulz predicted the new government would have "the paramount challenge to work for a peaceful solution to the conflict, launch an economic rebirth with the help of Ukraine's partners, kick-start key reforms, especially with regard to the rule of law and the judicial system and rooting out chronic corruption".
Elmar Brok, chair of parliament's foreign affairs committee, viewed the election result as "a clear mandate now for president Poroshenko and prime minister [Arsenij] Jazenjuk to continue their pro-European agenda with full democratic legitimacy".
Brok said that he had spoken with the Ukrainian president, who told him he would enter into negotiations with the prime minister's party as well as the pro-European, Christian democrat Samopomich party headed by Andriy Sadovyi, in order to form a government.
The MEP warned that "Russia ought to swiftly contribute to the implementation of the Minsk agreement and accept a sovereign Ukraine". He added that this was necessary in order for "the relationship between the EU and Russia [to be] rendered sustainable".
"The EU must help Kyiv on the path of peace stabilisation and the democratisation process" - Gianni Pittella
Brok said that parliament "will support that course and help with the full implementation of the EU-Ukraine association agreement".
S&D group president Gianni Pittella highlighted that "Ukraine needs very deep economic and institutional reforms in order to aspire to a genuine European perspective". He stressed that "the EU must help Kyiv on the path of peace stabilisation and the democratisation process".
Tibor Szanyi, S&D group spokesperson during the election observation mission to Ukraine, also pointed out that the country needs European support, saying, "we need to help Ukraine to reach an agreement with Russia on gas and make sure that the international assistance will be used to provide social assistance to those in need".