In a survey of 15 countries, Scotland came bottom in two categories, one ranking physical activity and the other screen-based leisure time.
The first so-called global matrix of children's physical activity assessed nine indicators, such as active play and active transportation, and awarded a grade between A and F.
Scotland scored an F in the overall physical activity league table and an F in the sedentary behaviour category, which found they spent too much time watching television and using computers.
The initial results of the Scottish study were published last October, but this is the first time children in Scotland have been ranked against other nations involved in the project.
England received a D plus for overall physical activity, while Ireland scored a D minus.
However, Scotland, England and Ireland performed well in the community and built environment category, which includes the availability of parks and playgrounds, all scoring B.
England was graded A minus for its active schools, while Scotland scored B for government strategies and investments.
John Reilly, professor of physical activity and public health science at Strathclyde University, who was involved in the research, said: "The global matrix reveals an interesting relationship between lower physical activity and higher sedentary behaviour in countries with better infrastructure, and we found this to be the case in Scotland.
"What comes out very strongly is there is great variation around the globe and no single country has found a magic formula to improve children's health.
"Countries tend to score well in some categories - such as in the community and built environment - but badly in other areas, such as overall physical activity. This suggests there is great untapped potential for nations to learn from each other to improve the health of children around the world."
The 15 countries that submitted data were America, Australia, Canada, Colombia, England, Finland, Ghana, Ireland, Kenya, Mexico, Mozambique, New Zealand, Nigeria, Scotland and South Africa.
The study found no one country is leading or lagging in all indicators but that each country has its own blend of successes and challenges.
New Zealand and Mozambique reported the highest grades (B) for overall physical activity, while 10 countries reported low or failing grades (D or F), suggesting there is widespread evidence of a childhood inactivity crisis.
New Zealand and Australia reported the highest grades (B and B minus respectively) for organised sport participation, while most other countries clustered around a C grade, indicating about half of children participated in sport.
Grades for active transportation, such as walking or cycling to school, ranged from B in Finland, Nigeria, Kenya and Mozambique, to F in America, while England and Scotland scored C and Ireland D.
Ghana and Kenya reported the best grades (B) for sedentary behaviour but, while there was significant global variation, the majority of countries had poor or failing marks in this category. Ireland scored C minus, while data for England was not available.
The Scottish data came from the first active healthy kids Scotland report card.