Morawiecki told reporters that Von der Leyen, who was nominated by the centre-right European People's Party, was a compromise candidate.
He added: "I am a cautious optimist. The president of the European Commission gives hope for a new opening.”
Morawiecki added that the votes of Euro-deputies from Poland’s ruling conservative Law and Justice (PiS) party had proved decisive in Von der Leyen being elected.
The German politician was backed for the top EU job by 383 members of the European Parliament on Tuesday evening in a secret ballot; 327 were against and 22 abstained. She needed an absolute majority of 374 to secure the post.
Poland had previously strongly opposed socialist-backed Dutch contender Frans Timmermans as a candidate to head the EU’s executive for the next five years.
Morawiecki told reporters earlier this month that Timmermans was not a candidate who would “unite Europe".
As the commission’s vice-president, Timmermans came under fire from Poland’s ruling Law and Justice party for criticising its sweeping changes to the country’s judicial system.
The changes caused a series of clashes between Brussels and Warsaw and sparked concern that the rule of law was being undermined in Poland. The conservative government in Warsaw denied such charges.
Source: PAP/Polish Radio