They'll include a 7th generation Intel core processor known as Kaby Lake clocked between 4.2 GHz with up to 4.5 GHz, Apple said Monday at WWDC in San Jose.
Apple showed off the line: 21.5-inch iMacs start at $1,099 (roughly converting to £850 and AU$1,470). There's also a 21.5-inch iMac with a 4K Retina display starting at $1,299 (roughly £1,005, AU$1,735). Then there's the 27-inch iMac with a 5K Retina display starting at $1,799 (roughly £1,395, AU$2,400). The 21.5-inch iMac will have up to 32GB in memory, and the 27-inch will go up to 64GB.
Both the 21-inch and 27-inch models will get two USB-C connectors with Thunderbolt 3. All 27-inch models along with some of the higher-end 21.5 inch iMacs will get a Fusion Drive. Plus, Apple is offering a solid-state drive option that will promise even faster speeds.
John Ternus, VP of hardware engineering, said the new iMac displays will be 43 percent brighter than previous models at 500 nits and be capable of showing one billion colors.
The rest of the Mac line, which includes Apple's MacBook laptops, will also be getting the Kaby Lake processor, starting at a 1.3 GHz Core i7 with Turbo Boost ranging on up to 3.6 GHz edition.
While PC sales, including notebooks, have been on the decline, Apple shipped about 3.4 million Macs in the first quarter of the year, which made for a 15.4 percent increase from the previous year, according to a May report from TrendForce. Apple's computer line still accounts for about 10 percent to 15 percent of its quarterly sales.
The new iMac desktops and MacBook laptops are available in Apple Stores starting June 7, and available to order online Monday.
This is a developing story. Follow our WWDC live blog for real-time coverage.