The 23-year-old – who made his international debut in last month’s T20 series against India – will be the club’s overseas player until Michael Klinger returns towards the end of May.
The opener will be available for Gloucestershire’s first five County Championship games starting with Essex at Chelmsford on April 10.
The Western Australia player was the third highest scorer in last year’s Sheffield Shield with 896 runs at an average of 47 – including a best of 211 – and he has continued his good form in this year’s competition.
Gloucestershire head coach Richard Dawson said: “He’s been performing really well for Western Australia in four-day cricket for the last few seasons batting at the top of the order. He will bolster our batting during that period and he also gives us cover with the gloves if required.
“I talked to him this week and his hunger to come over and have a crack at county cricket really impressed me. He wants to come and learn and improve his game and that was massive for me.”
Bancroft was called up to the Australia Test squad for the tour to Bangladesh in October which was scrapped due to security fears.
He made his international bow in the recent T20 series with India after impressing as wicketkeeper/batsman for the Perth Scorchers in his first full Big Bash League campaign.
The Australia A batsman has also been prolific in domestic one-day cricket – averaging 55 in the Matador BBQs Cup.
Bancroft is a team mate of Gloucestershire’s other Australian stars Andrew Tye and Michael Klinger – who gave the new signing his backing.
Dawson said: “Maxy (Michael Klinger) has given him really good reviews – he said he’s very fit, hard-working and is committed to trying to improve and kick on.
“His attitude and the fact that he is 23 means he is a really good fit for our changing room which is also important.”
The first opportunity for fans to see Bancroft in competitive action for Glos at the Bristol County Ground is likely to be their first home Championship game v Derbyshire on April 17. He will also be available for the home games against Worcestershire and Glamorgan and the trip to Canterbury.
Cameron said: “It is a great honour to be given the opportunity to come and play for Gloucestershire County Cricket Club at the beginning of the season. The club comes with a great history and I am looking forward to being a part of that and contributing plenty of runs to help drive this team to success this season. I can’t wait!”