The world's No.4 PC vendor posted a net profit of T$100 million ($3.38 million) in October to December, below a consensus forecast of a T$202.24 million from 16 analysts polled by Thomson Reuters I/B/E/S.
The figure compares with a net loss of T$1.1 billion in the third quarter and a net profit of T$$3.9 billion in the same quarter a year earlier.
But the company still posted a loss of T$6.6 billion for the full year 2011, hurt by one off charges, compared to a net profit of T$15.1 billion in 2010.
"After the operational and strategic adjustments from Q2 2011, Acer's current financial and business operation is becoming more healthy and stable," the company said in a brief statement.
It did not elaborate further but will hold an investor conference to give first-quarter outlook at 0830 GMT. ($1 = 29.5730 Taiwan dollars)
(Reporting by Clare Jim; Editing by Jonathan Standing)