Sales of the company's earlier iPads had been on the decline.
Apple said the "3D touch" feature of its new phones "transformed" the experience of using them by making it easier to use and switch between apps.
Huawei demonstrated its own version of the feature - which it called "force touch" - at its own launch event last week.
Apple sold 19% fewer iPads between the start of October and the end of June as it did during the same period a year earlier.
One expert suggested that the new model could reinvigorate sales.
"As much as the iPad is experiencing some challenging times, it's vastly more successful than any other tablet on the market and it's still a multi-billion dollar business," said Geoff Blaber from the CCS Insight consultancy.
"Moreover, what's happened is there's been cannibalisation from larger screened iPhones.
"A larger-screened iPad should definitely breathe some life into the category. But the price will be a barrier for many."
Apple said the new tablet offered similar processing power to 80% of the portable PCs that were sold over the past six months.
The iPad Pro will be launched alongside an optional magnetically-connected keyboard - which resembles a similar accessory for Microsoft's Surface tablet.
In addition, the firm announced a stylus called the Apple Pencil, which has sensors in its tip to help mimic the effect of using a real pencil on paper.
The announcement is notable since the firm's ex-chief executive Steve Jobs said in 2010: "If you see a stylus, they blew it."
Apple said the iPad Pro should run for 10 hours of use between charges and would be available in November and range from $799 to $1,079 (£520 to £702) depending on its level of storage and 4G connectivity.
The Pencil costs $99 and the keyboard $169.
Tablet computing is great, but it could be said that the iPad's Achilles heel was that it was great as a consuming device, but if you wanted to really do something, get work done, it wasn't ideal.
Apple is trying to address that with the iPad Pro. It's enormous, but not bulky, even if it does come in heavier than the original iPad at 1.67lbs (0.76kg).
Crucially, it has some intriguing input devices.
It's easy to scoff at Apple making a crowd cheer and whoop at a "pencil", but it's a big step forward for the most popular tablet on the market.
Making the iPad a "doing" service makes it a really formidable product, and one that should eat into netbook sales.
Apple TVChief executive Tim Cook also unveiled a new set top TV box with its own app store and new operating system.
The device uses a remote control that features a touch-sensitive panel and a microphone that allows it to be voice-operated.
It uses the firm's Siri virtual assistant to let owners ask what shows or movies based on their desired themes or favourite actors are available, and can bring back results from a range of services.
In addition, it can play video games.
"The future of TV is apps," declared Mr Cook. The firm had previously described its TV boxes as a "hobby".
Apple was one of the first tech companies to offer an internet-connected TV box, but Amazon, Roku and several smart TV-makers beat it to offering an app-focused experience.
Mr Cook acknowledged it had taken his company several years to introduce a TV app store.
"I don't think they have missed an opportunity by waiting until now," commented Ian Maude from Enders Analysis.
"There's a lot of people out there who want to watch content that is only available online from the TV, and if Apple can show its device does things better than the alternatives you would expect them to start winning market share pretty quickly."
Apple did not unveil a rumoured TV shows and movies subscription package of its own for the box, but Mr Blaber suggested that might follow next year.
"Broadcast content remains the challenge but growth in Apple TV will ultimately leave content providers with little option," he said.
Much of the Apple TV presentation was dedicated to the video games it can play. The remote is motion sensitive, and works in a similar fashion to Nintendo's Wii controllers.
The US firm has already had huge success with video game sales on its iPhones.
But one industry watcher questioned how disruptive the new box would be as a gaming device.
"There are already plenty of examples of set-top boxes and micro-consoles that play games, but none of those has had a dramatic impact on the market," commented Piers Harding-Rolls from IHS Technology.
"That's not to say that Apple entering the market won't be significant.
"But when you think of what the high-end consoles can do - allowing things like Sony's forthcoming Morpheus VR headset - what they offer can't be replicated in terms of power."
The TV box will cost either $149 or $199 depending on how much storage the user wants.
The idea behind the new iPhone's 3D Touch feature is that users can call up different functions by pressing the handsets' screens firmly.
Examples of how it can be used include:
- previewing an email or photo
- swapping weapons in a video game
- quickly switching into selfie photo mode
The handsets also gain the ability to shoot 4K videos - which means four times the amount of pixels of 1080p high definition video.n addition, their back cameras have been upgraded to offer 12 megapixels rather than eight - Apple said it had ensured the extra resolution had not come at the cost of more noise.
The iPhones also get a processor boost. They will go on sale in a fortnight's time.
One expert remarked that the upgrades were not as big as had been seen in some years, but were likely still enough to continue year-on-year sales gains.
"In developed markets Apple has a huge potential to sell to existing iPhone users who were not able to upgrade when the iPhone 6 launched because they were tied to contracts and then decided to wait until now," commented Francisco Jeronimo from the research firm IDC.
"But in markets like China it's about attracting new users.
"Those who were not attracted by the iPhone before will probably continue not to be interested.
"For the others, the new features themselves will not make a significant difference - it's more important for Apple to grow awareness of its products."
Watch updateApple also announced an upgrade to its smartwatch operating system that will be released on 16 September.
Watch OS 2 will allow third-party apps to run natively on the device rather than relying on a linked smartphone's processor.
I n addition to loading faster, the apps will also gain the ability to play video and access the Watch's microphone and sensors.
GoPro is taking advantage of this to allow users to see live streams from its action cameras on Apple's wearable.
Facebook also revealed it is bringing its Messenger app to the platform.