| Irvine | Robt. | Oakfield Farm, Yellingup, East Katanning | 7NE | 1924 |
| Irvine | Wm. G. | Onslow Creek, Carnarvon | CQ1 | 1924 |
| Irvine & Irvine | - | Bedarlo, Bencubbin | 1ZY | 1924 |
| Irvine & Son | C. R. | Riverview, Busselton | 1ZY and 6B, 51F | 1962 |
| Irving | A. N. G. | Kojonup 5967, 6498, Cranbrook | 7GV and 26B 12E | 1962 |
| Irving | Archd. Nigel Guy | Gingelup, Bon Shaw, Cranbrook, Kojonup | 7GV | 1924 |
| Irving | F. W. MacG. | Bonshaw, Cranbrook | FV6 and 40A, 4C | 1962 |
| Irving | Geo. | Bonshaw, Kojonup | 8GG | 1912 |
| Irving | Geo. | Bonshaw, Kojonup | 8GG | 1924 |
| Irving | George | Townfoot, Parker's Road, Souther Cross | Q0Y | 1925 |
| Irving | I. N. | Koorda | 9VN | 1924 |
| Irving | Margaret L. | Merrie Shields, Tenterden | M9V | 1924 |
| Irving | R. C. | Bealing Wellington Loc. 206, Lowden | XF8 and 11A, 14C | 1962 |
| Irving | W. W. | Merrie Shields, Cranbrook | M9V and 80B, 47A | 1962 |
| Irving & Douglas | - | Chenus Station, Nannine | 1DN | 1912 |
| Irving & Smith | - | Mooloogool, Meekatharra | O4O | 1924 |
| Irving & Smith | - | Mingah, Meekatharra | OO4 | 1924 |
| Irving & Son | G. | Townfoot, Moorine Rock | Q0Y and 8B, 48E | 1962 |
| Irwin | A. E. | Homestead, Dowerin | AE6 | 1912 |
| Irwin | A. E. | Homestead, Dowerin | AE6 | 1924 |
| Irwin | P. | Napier. 5861, Albany | P1J and 19A, 108B | 1962 |
| Irwin (Upper) Roads Board | - | Commonage and Reserves, Box 16, Mingenew | U2R | 1924 |
| Isaac | M. B. | Lots 98, 99, 100, 489, Tambellup | Y1S | 1912 |
| Isaac | M. B. | Lots 98, 99, 489, Tambellup | Y1S | 1924 |
| Isaacs | Chas. F. | Boomerang. Peel Estate, Jandakot | 1FQ | 1924 |
| Isaacs | M. A. E. | Town Lot 28, Margaret River | 1ZS | 1962 |
| Isaksen | Hilmer | Ranch Farm, Katanning | H1T | 1912 |
| Isaksen | Hilmer | Ranch Farm, Katanning | H1T | 1924 |
| Isbister | F. W. | Westbank, York | FW8 | 1912 |
| Isbister | F. W. | Westbank, York | FW8 | 1924 |
| Isbister | G. W. | Fargo, Kwolyin, via York | Y9K | 1924 |
| Isbister | M. L. | Ranfurly Park, Moora | M1Z and 16D, 107E | 1962 |
| Isbister Bros. | - | Glenorchy, Williams | 1BW | 1912 |
| Isbister Bros. | - | Glenorchy, Williams | 1BW | 1924 |
| Isdell | Jas. | P.O. Hall's Creek | 2JU | 1912 |
| Isdell | Jas. | P. O. Hall's Creek | 2JU | 1924 |
| Isdell Pastoral Co. Ltd. | - | Isdell Station, via Derby | UY0 | 1924 |
| Isele | F. F. | Mariginup Lake, Wanneroo | FV4 | 1924 |
| Iseppi | C. | Woodland Park, Hamel | UH3 and 50B, 10E | 1962 |
| Iseppi | J. H. | Block 55/66 Drake-Brook District, Waroona | 1JH and 11C, 26E | 1962 |
| Ison | Edward | Tablelands, Roebourne | NS0 | 1924 |
| Ispen & Sons | J. B. | Chungarrup, Manjimup | J1E and 20B, 112E | 1962 |
| Isseka | Jack | Four Mile Well, Murchison River, Northampton | J3O | 1912 |
| Isseka | Jack | Four-Mile Well, Murchison River, Northampton | J3O | 1924 |
| Italiano | C. | 5135-4-3-2 Woodinilling Locs, Kojonup | CJ7 and 12B, 36E | 1962 |
| Italiano | D. A. | Port .Wellington Loc. I being part of each lot 29, 30-1, on plan 2003, Brunswick Junction | DA9 and 34D, 8E | 1962 |
| Italiano | G. | Block 1831, Bindoon | GT7 and 40A, 12B | 1962 |
| Italiano | P. & F. | 37 Pt. 128, Dardanup | 1RO and 38C, 103E | 1962 |
| Italiano & Sons | P. (Mrs) | Wellington Loc. Lot 802, 1A, Harvey | P2S and 9B, 24E | 1962 |
| Ittershagen | Hermann C. | Thuringia, Manjimup | 1TZ | 1924 |
