About 2.1 million people watched the second election debate, televised live on Thursday night, compared with 1.75 million viewers for the first debate.
Political commentator Li Pang-kwong, of Lingnan University, said the bigger audience reflected that the public's sense of involvement in politics had increased slightly.
A senior government official said the debates were of no help to the public in gaining a better understanding of candidates' policies.
The second 90-minute debate was organised by the city's eight electronic media organisations and was broadcast in prime-time starting at 8pm.
Spokesmen for free-to-air broadcasters TVB and ATV said the average viewer rating for the debate was 32 points, with the highest rating 35.6 points - equivalent to 2.07 million viewers and 2.3 million viewers, respectively, for the TVB Jade and ATV Home channels.
Dr Li said there were several reasons for the good ratings, including the fact the debate was broadcast in prime time and viewers were interested in watching the first election debate in which members of the public were in the audience.
