Announcing the plan in Cape Town, IRB chairman Dr Syd Millar said: "This is an historic day for rugby as it represents an unprecedented level of investment in rugby worldwide."
The three-year programme, which has been approved by the IRB's executive committee, will see seven so-called tier two unions - Fiji, Samoa, Tonga, Canada, USA, Japan and Romania - share Â£15.5million worth of investments, with Â£3million earmarked for "high performance initiatives" in the Pacific Islands.
Further investment in tier one unions, including the likes of England and Wales, is also planned, while Argentina will receive Â£750,000 towards high performance requirements and an additional Â£1.5 million for establishing new domestic structures and a cross-border tournament.
Some Â£1.5million has been set aside for tier three unions, and the Â£30million package is in addition to an annual Â£12million investment in all 120 IRB member unions.
The new cross-border competitions include plans for a Pacific League, comprising regional teams from Fiji, Samoa and Tonga, a North America Six and South America Eight, when six Argentinian sides will be joined by one each from Chile and Uruguay.
Exact details of these new competitions - which will be played during June and July - should be announced in November.
It is also intended to expand the Churchill Cup - won this year by England - to include A teams from other countries, while a Rainbow Cup featuring South Africa A and Romania, among others, is also mooted.
"To make lasting change you need commitment, people, infrastructure and competitions," added Millar.
"That is exactly what we are putting in place, and it will make a real difference to the tier two unions in terms of increasing their competitiveness.
"Ultimately, the aim is to ensure that more unions can challenge for, and potentially win, the Rugby World Cup.
"The continued growth of the Rugby World Cup is vitally important for the sport, which only went professional 10 years ago.
"While rugby has come a long way in that short period, this investment represents a huge statement in terms of our confidence in the future prosperity of rugby. The maintenance of our traditional base is a priority, but we also have to move rugby into new markets and continue to grow the developing markets.
"This is a massive investment programme that should have a significant impact on world rugby."