Juncker will present details of the ambitious plan to a session of the European Parliament, which is sitting in Strasbourg, France, at 9am, the official parliamentary schedule said.
Parliament’s political groups will be able to respond afterwards.
The plan is the centrepiece of a wide-ranging reform agenda by the former Luxembourg premier, who took charge of the Commission, the 28-nation European Union’s executive branch, on November 1.
But it has been overshadowed by a row over revelations about huge tax breaks for international firms that Luxembourg handed out during Juncker’s 19 years as premier.
Juncker faces a no-confidence motion in parliament filed by eurosceptic and far-right groups over the revelations.
There will be a debate on the issue on Monday and a vote on Thursday, according to the parliamentary schedule.
However Juncker is almost certain to pass with the backing of his centre-right European People’s Party and the Social Democrats of European Parliament President Martin Schulz.
It caps a busy week in the European Parliament, with a speech by Pope Francis due on Tuesday.
Juncker’s investment plan has so far been big on rhetoric but thin on details, leading to fears about how much money will actually be pumped into the fragile EU economy.
Global concerns have mounted about the health of the 18-nation eurozone, or countries that use the euro, just two years after the EU said that the debt crisis which started in 2009 was over.
Spiralling youth unemployment, near-zero growth and the spectre of deflation – falling prices that would further hurt the economy – have led to worries about a lost decade for the continent.
French Economy Minister Emmanuel Macron called earlier this week for the investment plan to be a “New Deal” – a reference to the 1930s US plan after the Great Depression – and saying that it should include as much real money as possible.
But reports have indicated that while there will be some new cash – for example 10 billion euros recently pledged by Germany and the freeing up of funds by the European Investment Bank – much of the 300 billion consists of creative accounting, using projected investments resulting from the seed money, or of already-existing EU funds.
The mix of private and public funding is also unclear and euro MPs will be hoping to hear more details on Wednesday.