Douglas Ross and Ross Thomson were both elected to Holyrood in 2016 but then won seats at Westminster in the snap general election.
Both are list MSPs, so will be replaced by fellow Conservatives.
Scotland is sending a total of 22 new MPs to Westminster following the election, alongside 37 re-elected incumbent members.
Meanwhile, Rachael Hamilton is being sworn in as a Conservative MSP for the second time in the current term, having quit her list seat to successfully contest the Ettrick, Roxburgh and Berwickshire by-election on the same day as the general election.
In last Thursday's general election, the Conservatives won 13 seats north of the border, their best return since 1983.
Mr Ross won the Moray constituency from the SNP's depute leader and Westminster group leader Angus Robertson, while Mr Thomson took Aberdeen South from Callum McCaig.
Both men were formerly councillors, on Highland and Aberdeen City councils respectively, and have gone from local politics to Holyrood to Westminster in just over a year.
The Scottish Parliament's additional member system means the two list MSPs will be replaced by Conservative party colleagues.
To replace Mr Ross, Jamie Halcro-Johnston is next on the Highlands list, having failed to win a seat in Orkney and Shetland in the general election.
Tom Mason, who is currently depute provost of Aberdeen City Council, is expected to take Mr Thomson's place from the North East list.
Mr Mason is the final name on the list, with all of the other candidates having been elected either to Holyrood or Westminster - or, in one case, left the party. If a party runs out of regional list members, then the seat is left empty for the duration of the parliament.
Two newly-elected Conservative MPs have resigned their seats in the Scottish Parliament.