The MP for Ross, Skye and Lochaber was confirmed in the roll this afternoon.
He replaces Angus Robertson who failed to hold the Moray constituency at last week’s general election.
The 56-year-old will be responsible for leading the third largest grouping of MPs in the House at a time when no party has an overall majority.
Blackford, originally from Edinburgh, was first elected to the House of Commons in 2015 when he won the seat previously held by former Lib Dem leader Charles Kennedy.
He worked as an equities manager for Deutsche Bank before leaving the financial services industry to take on independent consultancy work.
Blackford twice stood as an SNP candidate in 1997, at a by-election in Paisley and in that year’s general election, but lost out to Labour candidates.
He later served as treasurer of the party from 1999-2000.