The Ulster hooker has been given the role after Paul O'Connell was ruled out for the remainder of the championship with the knee ligament damage sustained in Sunday's 17-17 draw with France.
Best, who has led Ireland twice before against Canada and USA in 2009, suffered a rib injury against Les Bleus but has been included in the starting line-up.
"It's a great honour to be asked to captain the side. It's something you dream of doing," Best said.
"It's very unfortunate that Paul's out but I'm honoured to do the job.
"We know we'll have to be on the money against Scotland. It will be a massive challenge for our defence."
Two changes have been made to the side that almost stormed the Stade de France with Donnacha Ryan replacing injured Munster team-mate O'Connell.
Eoin Reddan starts at scrum-half after Conor Murray was also ruled out for the last two matches against Scotland and England because of a knee injury.
Ireland team to face Scotland at Aviva Stadium, Dublin, on Saturday, March 10(kick-off 5pm):
R Kearney (Leinster); T Bowe (Ospreys), K Earls (Munster), G D'Arcy (Leinster), A Trimble (Ulster); J Sexton (Leinster), E Reddan (Leinster); C Healy (Leinster), R Best (Ulster, capt), M Ross (Leinster), D O'Callaghan (Munster), D Ryan (Munster), S Ferris (Ulster), S O'Brien (Leinster), J Heaslip (Leinster).
Replacements: S Cronin (Leinster), T Court (Ulster), M McCarthy (Connacht), P O'Mahony (Munster), T O'Leary (Munster), R O'Gara (Munster), F McFadden (Leinster).
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