Rated as the No.1 batsman in both Test and ODI cricket, the 34-year-old will be available for the first three months of the County Championship and Royal London One-Day Cup.
Amla's selection means George Bailey will not make a return to the Hampshire squad, with team's head coach Giles White also conforming that the Australian player would not be signed to replace the South African in the second half of the 2018 domestic season.
Describing Amla as a `world-class player`, White said that the former is an exciting acquisition for the team and that he would fit well for them both on and off the pitch.
"Hashim is an exciting acquisition for us and we feel he'll be an excellent fit within the group we've got, both on and off the pitch. He's a world-class player and this addition adds strength and depth to our batting for the first three months of the season," ESPNcricinfo quoted Amla, as saying.
Amla, on the other hand, said that he is looking forward to spend first three months of the season with Hampshire and gain some high-quality cricket ahead of his side's tour to Sri Lanka.
"I am really pleased to be joining a club like Hampshire. Everyone I have spoken to, who have either played or are currently playing there, have only had good things to say about the team. I look forward to spending the first three months of the season with them, which works out well for me to be able to get some high-quality cricket in before the Proteas tour to Sri Lanka in July," Amla added.
Amla, who previously had spells at Essex (2009), Nottinghamshire (2010), Surrey (2013-14) and Derbyshire (2015), will join compatriots Kyle Abbott and Rilee Rossouw, who both had quit South Africa international duty just over a year ago.(ANI)