Keogh, a try scorer in the 25-16 win over Plymouth Albion at Greystones RFC last weekend, forms a back row partnership with Eoin Sheriff and Jordi Murphy.
Argentina international Mariano Galarza locks down with Ed O'Donoghue in the second row, with powerful prop Stewart Maguire starting in the front row alongside Jack McGrath.
Paul O'Donohoe forms a half-back partnership with Ian Madigan, and youngsters Brendan Macken and Noel Reid link up as Leinster's starting centres.
LEINSTER (v Cornish Pirates): Niall Morris; Darren Hudson, Brendan Macken, Noel Reid, Andrew Conway; Ian Madigan, Paul O'Donohoe; Jack McGrath, Aaron Dundon, Stewart Maguire, Mariano Galarza, Ed O'Donoghue, Eoin Sheriff, Jordi Murphy, Stephen Keogh (capt).
Replacements: Tom Sexton, Simon Shawe, Mark Flanagan, Ben Marshall, John Cooney, Ian McKinley, Michael Keating.