The hotly anticipated addition to Google's Nexus line is powered by a new "KitKat" version of Android, which was redesigned to work across the wide range of handsets built with the Internet titan's free software inside.
"Now you have one version of the Android operating system that can ship across all versions of smartphones in 2014," Sundar Pichai, head of the Android and Chrome teams, said while providing a look at the new software and Nexus 5.
"As we get on our way to reach the next billion people, we want to do it with the latest version of Android."
The move aims to solve the problem that the wide variety of Android systems used around the world make it challenging for makers of fun, functional or hip smartphone or tablet apps to design programs that work on all devices.
Being stuck with old versions of Android also means that users don't get access to upgrades or improvements cranked out by Google.
Apple executives routinely boast about how most users of its iPhones, iPads and iPod touches are on the latest version of the iOS operating system while many Android users are stuck with old versions.
Changes in KitKat included fine tuning it to work with the limited memory capacities of Android smartphones priced for markets in developing countries or other places where buyers are on tight budgets.
"It is important to us to get the same version of Android to scale across all versions of devices," Pichai said.
Google partnered with South Korean consumer electronics giant LG to make the Nexus 5 smartphone to showcase the prowess of KitKat.
The Nexus 5 was available for purchase in 10 countries through Google's online Play shop, priced at $349 for a 16-gigabyte model and $399 for a version with 32 gigabytes of memory.
KitKat was released to handset makers to begin building their own smartphones using the software, according to Pichai.
"It is a cutting-edge operating system meant to run on cutting-edge phones, but it can run on older phones as well," Pichai said.
It is up to Android smartphone makers whether to push KitKat updates to people using their devices running on old versions of the operating system.
"The idea is to finally unify all of the Android operating systems to the point where they stop fragmenting," said analyst Tim Bajarin, president of Creative Strategies in Silicon Valley.
"Vendors have every reason to keep their customer bases happy."
KitKat improves the smartphone user interface with richer and more immersive graphics while tapping into Google data centers for features such as anticipating what smartphone users wants to see before being asked.
For example, a KitKat-powered smartphone can recognize when you are near a movie theater and automatically pop up film times.
KitKat also takes into account what most people do at a certain spot to predict what a smartphone user might want, Pichai explained.
If the software noticed a person was by Old Faithful geyser in Yellowstone National Park it would automatically display information about when it was due to spout.
If an incoming telephone call is from a business, information from its website will be displayed as the handset rings.
"Our vision is that every time you pick up the phone, the information you want is right there in front of you," Pichai said.
"This is the kind of thing we really get excited about doing; bringing the power of Google smarts to the device."
Making KitKat the one Android operating system to rule them all will help Google's position in smartphones, according to Bajarin.
Google is both a rival and an ally to Android smartphone makers.
While Google has worked with partners to make Nexus brand smartphones for several years, its acquisition of Motorola Mobility last year has made it a competitor in handset hardware.
Leading Android smartphone maker Samsung this week held its first developers conference to encourage creation of apps for its devices, particularly those powered by the South Korean consumer electronics giant's own Tizen software.
"Samsung is very much at odds with Google," Bajarin said.
"Samsung is only going to continue to win if they control their own destiny," he continued. "If they have to rely on Google their future is limited."
Google, Apple and Microsoft each control smartphone hardware and software to lure fans with mobile device "ecosystems" and Samsung likely intends to follow suit, according to the analyst.
"Samsung will be in a tough place if they don't end up controlling the operating system themselves," Bajarin said. "Right now, they are beholden to Google."