The report, compiled by Econactive on behalf of the Welsh Rugby Union (WRU), was unveiled at this week's Event Wales International Conference in Cardiff by first minister Carwyn Jones.
Jones was highlighting the importance of major events to Wales's economic development and regeneration, and stressing how government, local authorities and sporting organisations should align their strategies to attract business.
The Millennium Stadium hosts around 770,000 paying visitors a year, including conferences and exhibitions. Econactive's report found that 70% of spend was non-local in origin, meaning it had an outside, additional economic impact on the Welsh economy.
Jones said: "The stadium is a key component of what Wales has to offer as a host of major events. The stadium has set its sights on attracting high-profile events of global importance, which have attracted more visitors from outside Wales."
A previous study by Econactive in 2007 found that the stadium generated £100m a year and sustained 2,400 jobs.
Roger Lewis, WRU's group chief executive, added: "We commissioned this report to show the significance of the stadium and the activities of the Welsh Rugby Union to Wales and we are determined to work hard to ensure we sustain the level of activity that delivers this long-term benefit to us all.
"This is why we constantly strive to work closely with local authorities, particularly Cardiff County Council and the Welsh Government, to align our strategies and do the very best we can for Wales."