There were 556 fatalities from 15 airliner accidents in 2018 - up from 44 deaths from 10 accidents in 2017, according to figures released by the Aviation Safety Network (ASN).
It means that 2018 was worse than the five-year average of 14 accidents and 480 fatalities - while 2017 was the safest year in aviation history, the ASN said.
Netherlands-based ASN said that 12 of the accidents in 2018 involved passenger flights, while three related to cargo flights.
The accident with the highest number of deaths in 2018 was October's Lion Air crash in Indonesia - which left 189 people dead.
The Boeing 737 Max plane crashed into the Java Sea shortly after take-off from Jakarta. It was reported that a preliminary study found it had previously suffered technical problems.
ASN suggests that safety has been improving over the past 20 years, and at a time when there has been strong demand for worldwide air traffic.
Chief executive Harro Ranter said: "If the accident rate had remained the same as 10 years ago, there would have been 39 fatal accidents last year.
"At the accident rate of the year 2000, there would have been even 64 fatal accidents. This shows the enormous progress in terms of safety in the past two decades."
ASN described loss of control (LOC) accidents as being a major safety concern in the aviation industry over the past five years, as these accounted for at least 10 of the 25 worst accidents - most of which were described as "not survivable".