The HSBC Emerging Markets Index (EMI), a monthly indicator derived from PMI surveys, rose to three-month high of 51.7, from November's six-month low of 51.2, but still signalled only a modest rate of expansion.
The EMI averaged 51.4 over 2014 as a whole, the lowest for a calendar year since the series began in late-2005.
"Although growth picked up slightly across the world's main emerging markets on an average, rates of expansion remain subdued," Markit Chief Economist Chris Williamson said.
Data for the four largest emerging economies portrayed mixed fortunes in December.
China registered growth for the eighth month running, while India's tentative recovery continued. Brazil saw a decline in activity for the eighth time in nine months, while Russia endured a steepening downturn.
During December, the HSBC composite index for India, that maps both manufacturing and services, stood at 52.9, whereas for China it was 51.4, Brazil (49.2) and Russia (47.2).
An index measure of above 50 indicates expansion.
"Of the four 'BRIC' economies, India saw the strongest rate of expansion in December, despite the rate of expansion slipping from November's five-month peak," said Williamson, adding that the rate of growth for both India and China slowed from an already "lacklustre pace".
The outlook for global emerging markets remained muted in December.
The HSBC Emerging Markets Future Output Index, which tracks firms' expectations for activity in 12 months' time, picked up from November's record low on the back of strengthening sentiment in Brazil and India.
Overall inflationary pressures across emerging markets remained subdued, HSBC said, adding that both new orders and employment in emerging markets increased in December.