The Ukrainian parliament's website said Poroshenko’s office submitted the nomination of Klimkin today to replace acting Foreign Minister Andriy Deshchytsya.
Klimkin's candidacy is expected to come up for a vote later this week.
Klimkin, 47, has been Ukraine's envoy to Germany since 2012.
He is a pro-European diplomat who has played a big part in talks on a political Association Agreement with the European Union.
Poroshenko also nominated Valeriya Hontareva as the new head of the central bank, to replace Stepan Kubiv.
Correspondents say Hontareva is an experienced banker who is respected in business and investment circles.
Her nomination must also be approved by parliament.
BBC global news audiences now at record 265m - Big rises in #Russia & #Ukraine: People rejecting the propaganda war? http://t.co/wcSsTjec7v
— Andrew Stroehlein (@astroehlein) June 18, 2014
Neuer ukrainischer Außenminister wird Pawlo Klimkin, bisher Botschafter in Berlin. Mein Text von letzter Woche: http://t.co/eJNvU1z8KU
— Claudia von Salzen (@claudi) June 18, 2014
Important to note that the decision to replace Deshchytsia has nothing to do with a certain statement about Putin, was planned before that.
— Claudia von Salzen (@claudi) June 18, 2014
After calling Putin a "khuilo," Ukrainian foreign minister @ADeshchytsia is to be replaced by Pavel Klimkin, ambassador to Germany.
— max seddon (@maxseddon) June 18, 2014
Poroshenko offers "amnesty" if fighters disarm, havent committed "grave crimes." Offers "corridor for unarmed mercenaries" to leave #Ukraine
— Kirit Radia (@KiritRadia) June 18, 2014
Interesting comparison here between Ukraine and Ireland, Donbas and Northern Ireland. http://t.co/kbm6YvRSC8
— Paul Sonne (@PaulSonne) June 18, 2014
. @PaulGoble1 on Russia's agitation in Ukraine's western Transcarpathia region. "a core part of Putin's agenda" http://t.co/FXIK3DX15N
— Robert Coalson (@CoalsonR) June 18, 2014
Arsen Avakov made the announcement at a government meeting today, a day after an explosion hit a pipeline carrying Russian gas to the rest of Europe.
The blast caused no casualties and gas flows were not interrupted.
Prime Minister Arseny Yatseniuk said the explosion was aimed at undermining "Ukraine's reputation as a reliable transit partner," and ordered security to be reinforced on the country's gas pipeline installations to prevent sabotage.
In Moscow, Gazprom predicted more "accidents" on Ukraine's gas transportation system, saying not enough is being spent on maintenance.
The explosion came after Moscow cut supplies to Kyiv in a long-standing pricing row and amid an uprising by pro-Russian separatists in Ukraine’s east.
Russia brings criminal charges against Avakov, Kolomoisky http://t.co/HOOVToadj5 pic.twitter.com/fmyHm8lKSO
— Kyiv Post (@KyivPost) June 18, 2014
Poroshenko told reporters in Kyiv on June 18 that he would soon order a "very brief" unilateral cease-fire as part of a broader plan to end the 10-week-long separatist insurgency.
The Kremlin earlier said that Poroshenko and Russian President Vladimir Putin discussed a possible ceasefire in eastern Ukraine in a telephone conversation on June 17.
They also discussed the deaths of two Russian journalists earlier on June 17 in the east of the country.
Meanwhile, Russian investigators said they had opened a criminal probe against the Ukrainian interior minister, Arsen Avakov, and the governor of Dnipropetrovsk region, billionaire Ihor Kolomoyskiy, accusing them of being behind the killings of peaceful civilians and journalists in the east.