The cardinal represents a fourfold acceleration on the absolute aftermost year.
The all-inclusive majority beyond by sea, with added than 800,000 travelling from Turkey to Greece. Most are refugees from Syria, Iraq and Afghanistan.
The IOM says 3,695 migrants accept drowned this year or abide missing.
Migrant crisis in graphics
Shelter or anguish in Athens
Desperate journeys
'We charge act'
The allegorical anniversary was anesthetized on Monday, the IOM said, with the absolute for acreage and sea extensive 1,005,504.
The amount covers entries via six European Union nations - Greece, Bulgaria, Italy, Spain, Malta and Cyprus.
Half of the refugees bridge the Mediterranean were from Syria, 20% were from Afghanistan and 7% from Iraq, the IOM says.
Most of the migrants who died - 2,889 - were authoritative the sea bridge amid arctic Africa and Italy, while added than 700 died in the Aegean bridge to Greece from Turkey.
Only 3.5% of migrants fabricated a acreage adventure to Greece or Bulgaria via Turkey.
The IOM gathers its statistics from registrations, law administration agencies and its own monitors.
But IOM administrator accepted William Lacy Swing said it was not abundant to aloof calculation the figures.
He said: "We charge additionally act. Migration charge be legal, safe and defended for all - both for the migrants themselves and the countries that will become their new home."
A joint IOM and UNHCR statement said "a more co-ordinated European response is beginning to take shape".
However, it said added bare to be done to advance accession facilities, accommodation, allotment and to analyze those who do and do not authorize for refugee protection
Frontex boost
Some states accept put up fences and alien bound controls admitting the EU's border-free Schengen area.
The EU aftermost anniversary agreed to access the numbers of Frontex bound bureau agents in Greece, a key accession point.
Once they access in Greece, abounding migrants again try to biking arctic via the Balkan states, abounding branch for Germany and the Nordic countries.
Germany abandoned has accustomed a actor refugees and migrants this year, although abounding were already aural Europe.
Macedonia is now abnegation to acquiesce anyone through its Greek bound who does not appear from a war zone.
A UN address aftermost anniversary warned that the cardinal of forcibly displaced bodies common would "far surpass" 60 actor this year.
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