| National party | Chairperson(s) | Seats | ± 2016 |
|---|
| {{Independence Party (Iceland)/meta/color}}|border=darkgray}} Independence Party | Bjarni Benediktsson | 16|63|hex={{Independence Party (Iceland)/meta/color}}|border=darkgray}} | {{Decrease}} 5 |
| {{Left-Green Movement/meta/color}}|border=darkgray}} Left-Green Movement | Katrín Jakobsdóttir | 11|63|hex={{Left-Green Movement/meta/color}}|border=darkgray}} | {{Increase}} 1 |
| {{Progressive Party (Iceland)/meta/color}}|border=darkgray}} Progressive Party | Sigurður Ingi Jóhannsson | 8|63|hex={{Progressive Party (Iceland)/meta/color}}|border=darkgray}} | {{Steady}} |
| {{Social Democratic Alliance/meta/color}}|border=darkgray}} Social Democratic Alliance | Logi Már Einarsson | 7|63|hex={{Social Democratic Alliance/meta/color}}|border=darkgray}} | {{Increase}} 4 |
| {{Centre Party (Iceland)/meta/color}}|border=darkgray}} Centre Party | Sigmundur Davíð Gunnlaugsson | 7|63|hex={{Centre Party (Iceland)/meta/color}}|border=darkgray}} | New |
| {{Pirate Party (Iceland)/meta/color}}|border=darkgray}} Pirate Party | Collective leadership | 6|63|hex={{Pirate Party (Iceland)/meta/color}}|border=darkgray}} | {{Decrease}} 4 |
| {{People's Party (Iceland, 2016)/meta/color}}|border=darkgray}} People's Party | Inga Sæland | 4|63|hex={{People's Party (Iceland, 2016)/meta/color}}|border=darkgray}} | {{Increase}} 4 |
| {{Reform Party (Iceland)/meta/color}}|border=darkgray}} Reform | Þorgerður Katrín Gunnarsdóttir | 4|63|hex={{Reform Party (Iceland)/meta/color}}|border=darkgray}} | {{Decrease}} 3 |