The US-based company is cutting the equivalent of 20% of its workforce. It will also close or merge around one third of its 90 production and research facilities.
Motorola, bought by Google last year for $12.5 billion (£7.9bn), also announced a strategic shift towards concentrating on what it described as "more innovative and profitable devices".
Two thirds of the jobs set to go are based outside of the US, Google said today in a regulatory filing, and the firm expects to incur severance-related costs of no more than $275 million from the action.
"Motorola is committed to helping them through this difficult transition and will be providing generous severance packages, as well as outplacement services to help people find new jobs," a statement said.
Motorola was once a major player in the mobile phone market, but it fell behind in the face of strong competition from Apple's iPhone and popular Samsung devices running Google's Android operating system.
In the first quarter of 2012, Samsung shipped more than 93 million phones to become the biggest player in the market. Motorola sold just 9m handsets in the same period, including around 5.1m smartphones.
According to recent financial results, Motorola Mobility recorded a loss of $86m in the first quarter of the year.
Some commentators have suggested that Google's primary motivation for acquiring Motorola Mobility was to gain the firm's more than 17,000 technology patents.
These can be used by Google to earn royalties and defend itself and other Android phone makers from patent lawsuits.
But Google said today that the restructure is aimed at returning the division to "sustainable profitability".
"These changes are designed to return Motorola's mobile devices unit to profitability," Google said in the filing.
"Investors should expect to see significant revenue variability for Motorola for several quarters.
"While lower expenses are likely to lag the immediate negative impact to revenue, Google sees these actions as a key step for Motorola to achieve sustainable profitability."
Dennis Woodside, the Google veteran who now leads the Motorola unit, said in an interview with Bloomberg in May that the firm would now focus on making fewer devices than the 20 it released last year.
He said that Motorola would concentrate on producing Android smartphones and tablets that drive innovation in the sector, and then back them with marketing resources to bring success.
"This is a huge opportunity to really show what Android can do in a well-designed, well-packaged, and well-marketed product," Woodside said.
Google is intent on increasing its hardware business to help it compete with rivals Apple and Microsoft. The company recently launched its new Nexus 7, a seven-inch tablet computer made by partner Asus.
But when it was given regulatory clearance for the Motorola deal in May, Google was told that it must keep the Android mobile operating system free for other device makers, such as Samsung and HTC, for up to five years, in order to safeguard competition.