An estimated £30m-£70m of road improvements will be needed on the Welsh island to accommodate works for the new nuclear power station.
The partners aim to select three to five firms for each of three lots covering works valued at less than £1m, £1-£5m and bigger projects.
Civil engineering firms have until 21 September to register there interest before a shortlist of firms are invited to bid in mid October.
Horizon Power is planing to start major on-site work in 2018 and first nuclear construction around 2020.
Further information can be obtained from the Sell2Wales website or from Emma Collett at the Isle of Anglesey County Council tel: 01248752313.