Finsbury partner Morgan Bone is leading the account which is believed to be worth around £100,000 a year.
Finsbury and two other unnamed agencies were considered for the work, awarded earlier this month on a retained basis.
The bank uses Icelandic agency Inntak PR in its home market.
Landsbanki senior director Larus Welding said: ‘We were the mandated lead arranger for [Icelandic investment company] Baugur Group’s acquisition of [UK jeweller] Goldsmiths in May. We underwrote that deal.
‘We got some press at that time, and when you are not represented you get bad press or very loose press. We wanted to make sure things were stated accurately and that we were understood correctly.’
Landsbanki has owned Heritable Bank since 2000 and operates in the syndicated loans and leveraged finance markets in the UK. Last month, Landsbanki made an unsuccessful bid for investment bank Numis Corporation.
It manages £4.5bn of assets, making it Iceland’s second-biggest bank by assets after Kaupthing Bank. Originally state-owned, Landsbanki was privatised in February last year and has a 30 per cent share of the country’s deposits and lending market.
Landsbanki also owns a 51 per cent stake in leasing company SP Finance.