Hun Neang died on Friday at the age of 90.
Yingluck’s visit comes two days after her brother, fugitive former premier Thaksin, was in the Cambodian capital to pay respect to Hun Sen’s father.
The state-owned National Television of Kampuchea reported that Thaksin paid tribute to the late Hun Neang on Sunday afternoon at Prime Minister Hun Sen 's residence near the Independence Monument in Phnom Penh.
The station added that Thaksin had expressed his condolences to Hun Sen and the PM extended his gratitude to him for traveling to Cambodia for the funeral.
Thaksin and his sister’s government have close ties with Hun Sen. Thaksin was an economic adviser to the Cambodian government and Hun Sen from November 2009 to August 2010.