SINN Féin's Martina Anderson is to become the third departing MEP to join the Stormont assembly.
The republican veteran's co-option means all three MEPs elected at last May's European Parliament election will now sit in the devolved assembly.
Ms Anderson joins the DUP's Diane Dodds and Alliance's Naomi Long, who replaced Carla Lockhart in Upper Bann and Máire Hendron in East Belfast, respectively.
She replaces Raymond McCartney, who was himself co-opted to the assembly in 2004 in place of Mary Nelis, before being elected three years later.
Ms Anderson becomes the ninth Sinn Féin co-option in the current mandate, which began in March 2017.
She previously served as an MLA for Foyle from 2007-2012, during which time she was also a junior minister in the Executive Office.
Her return to the assembly brings the total number of MLAs co-opted since the last Stormont election to 17 out of 90.
Sinn Féin said the former MEP was the sole nomination for the vacant Foyle MLA's role, for which a selection convention will be held later today in Derry.
Ms Anderson and Mrs Dodds's new roles mean they will receive a reduced transitional allowance from the European Parliament, which is offset against their assembly salaries.
Mrs Long does not qualify for the so-called end-of-term allowance because she served in the European Parliament for less than a year.
At the end of their term departing MEPs are provided with a transitional allowance that equates to their salary for one month per year they were in office. The maximum duration of this allowance is two years.
Mrs Dodds can claim the allowance for 11 months, while Ms Anderson can claim eight months.
Those MEPs who opt to take a pension when they are 63 are not entitled to a transitional allowance.
