The draft directive would require 75% of the packet to be covered - front and back - with the warnings. But company branding would not be banned.
It would also ban strong flavours such as menthol or vanilla, which can mask the bitter tobacco taste.
The revisions to the EU's 2001 tobacco directive could become law in 2014.
"Tobacco products should look and taste like tobacco products," said EU Health Commissioner Tonio Borg, presenting the proposals.
The current requirement for health warnings on packets is 30% minimum coverage on one side and 40% on the other.
The new packaging requirements would also apply to roll-your-own tobacco.
The legislation would allow member states the option of plain, non-branded packaging "in duly justified cases".
Words like "light", "mild" and "low tar" are deemed to be misleading and would be banned.
The Commission says packets must be big enough to ensure full visibility for the health warnings, so the recommendation is at least 20 cigarettes per pack.
Fourteen EU states already have 20 as the minimum, four stipulate a minimum of 19, and in the UK and Italy the minimum is 10. It is also argued that bigger, more expensive packets are less attractive to young smokers.
The EU would maintain its ban on chewing tobacco - called snus. Only people in Sweden can use it, under an exemption acknowledging the country's snus tradition.
The Commission says almost 700,000 Europeans die from smoking-related illnesses each year - equal to the population of Frankfurt or Palermo. The associated costs for healthcare in the EU are estimated to be at least 25.3bn euros (Â£20.6bn; $33.4bn) annually.
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Cigarette packs sold in the EU will have to have bigger health warnings in text and pictures, under new proposals from the EU Commission.