Analysis by Derrick Petroleum and PLS shows total deal value surged 50% higher than 2011, eclipsing the previous record of $212 billion set in 2010.
However, three mega-deals accounted for $97 billion of the spend.
The deals included Rosneft's $62 billion acquisition of TNK-BP, CNOOC's $18 billion acquisition of Nexen, and Freeport-McMoRan Copper's $17.2 billion buy of Plains Exploration & Production.
Excluding those three deals, the global M&A was on par with the five-year annual average of $160 billion.
PLS also noted M&A activity picked up towards the end of the year, which was driven by more than festive cheer.
"Also, during Q4 2012, we witnessed an unusually high level of deal activity totalling $137 billion in 181 deals as many sellers were motivated to complete deals in advance of the uncertainties surrounding the second term of President Obama and the implications of US governmental policy changes regarding the fiscal cliff," Managing director of PLS Brian Lidsky said.
The study also found that a relatively stable oil price helped in driving activity, but Asian national oil companies continue to be the big dogs of the M&A space.
The thirst of the NOCs to shore up supplies was in evidence during the year with CNOOC's acquisition of Nexen, Sinopec's $2.5 billion buy of Nigerian assets from Total, PetroChina's $2.2 billion joint venture bid for Encana's Canadian asset, CNOOC's buy into the QCLNG project and PetroChina's buy into the Browse LNG project.
All up, 679 M&A deals were completed during the year with the US leading the way with 33% of the activity, and Canada increasing its share of M&A to 28%.
The study's authors predicted a quiet start to the year, with more than a few executives sporting a hangover from the end-of-year blitz.
They also predicted that US gas prices might have stabilised, production from the Gulf of Mexico would return to normal, east African discoveries would make the headlines, Asian and Chinese firms would continue to dominate the landscape, and political unrest in the Middle East would be ongoing.