Chief Executive Carrie Lam officiated at the event, which began with those present singing the national anthem.
The legislators-elect then took turns according to their seniority to swear allegiance to the Hong Kong SAR and the Basic Law, with Tommy Cheung, Jeffrey Lam and Andrew Leung taking the lead.
FTU lawmaker Luk Chung-hung and Tik Chi-yuen had to re-take their oaths, with Luk missing out the word “lawmaker” on his first attempt, and Tik omitting the words “Hong Kong”.
Luk said afterwards that he had been a bit nervous.
The DAB’s Gary Chan did not raise his right hand as he took his oath, but he was not required to make the pledge again.
He said as he understands it, the rules do not require lawmakers-elect to raise their right hand, adding that he had taken his oath in an honest, accurate and solemn manner.
Most lawmakers took their oaths in Cantonese, except Tommy Cheung who made his pledge in English, and Chow Man-kong, Sun Dong and Tan Yueheng, who spoke in Putonghua.
A number of legislators also swore on the Bible.