Mrs Hamilton was born and attended school in Brecon, Wales, and after reading out her allegiance in English, decided to do it again in the language of her youth.
She said: “Rydw i, Rachael Hamilton yn rhegi y byddaf yn ffyddlon ac yn dwyn gwir deyrngarwch i'w Mawrhydi y Frenhines Elizabeth, ei hetifeddion a'i holynwyr, yn ôl y gyfraith, felly helpwch fi i Dduw.”
This translates to: “I, Rachael Hamilton do swear that I will be faithful and bear true allegiance to Her Majesty Queen Elizabeth, her heirs and successors, according to law, so help me God”.
Scottish Conservative Mrs Hamilton said: “It was an honour to be sworn into the new session of the Scottish Parliament and to be re-elected to represent the people of Ettrick, Roxburgh and Berwickshire.
“I took my oath of allegiance in Welsh as I was born and educated in Brecon.
“My family still live in the area along the Welsh border, and I have a strong affinity to the area.
“My priority, after my re-election, remains to give 100% of my efforts to the Borders and to stand up for my constituents in Holyrood.
“As we emerge from the Covid pandemic, we must be focused on recovery, attracting new employment opportunities to the Borders and ensuring we build back better.
"Borderers have placed their trust in me; I shall not let them down.”