O'Brien has been speaking to West Ham's official website as the players begin to settle into life under Bilic, who was appointed successor to Sam Allardyce last month.
The Hammers have already played their first competitive game of the season thanks to their involvement in Europa League qualifying.
They cruised to a 3-0 win over Andorran minnows FC Lusitans in that match to get Bilic's new era off to the perfect start.
After spending almost all of last season playing second fiddle to the brilliant Carl Jenkinson, frozen out Republic of Ireland international O'Brien was back in action during the Europa League win which attracted a sell out 35,000 crowd.
But just one game in O'Brien says his new boss is already under pressure to do well on his return to the Boleyn Ground, which will be torn down next summer when the club moves to the Olympic Stadium.
"Expectations get higher every year, to finish higher each time and the new manager will have that," O'Brien told whufc.com.
"It’s always been the same."
"We are going into the last season here at the Boleyn Ground and then into a new stadium, so there is a lot to go for.”
Joey O'Brien, West Ham's forgotten man
O'Brien was one of Sam Allardyce's key players since his signing in 2011. He played 65 league games in his first two seasons as the club got promoted and then reestablished themselves back in the Premier League.
But he made just nine league appearances for the Hammers last season, the least since he joined the club.
Such was the superb form of England fullback Jenkinson, who was on loan from Arsenal, O'Brien found game time hard to come by.
Future in the balance?
Despite starting and playing relatively well in West Ham's return to European competition for the first time in nine years, O'Brien does not appear to have much of a future in the club's starting XI if speculation is to be believed.
That's because the Hammers are being heavily linked with a permanent move for the 23-year-old Gunner by the likes of the Mirror.
The club is also said to be weighing up a swoop for ex West Ham academy prodigy Glen Johnson on a free transfer, as per the Express.
But given his experience and versatility - O'Brien can play at right back, left back, centre half and in midfield - and the fact Guy Demel, the man who had kept him out of the team before Jenkinson, has now left the club he could have a future yet under Bilic.