Central midfielder Osman has impressed during a trial with the Maryhill club and signed a one-year deal yesterday.
The Ghana-born player is vastly experienced having played for Gretna, Northampton Town, Crewe Alexandra and Kerkyra in Greece previously in his career.
The 27-year-old is hopeful he will be able to feature in Alan Archibald's side in the 2014/15 campaign.
He said: "I've enjoyed my time here so far. I came on Friday and trained with the lads and then played for 45 minutes of the game with Dumbarton on the Saturday.
"That was a good run-out. The boys have been good with me and the gaffer has been good with me. I am really happy to have signed.
"I can act as a ball-winning defensive central midfielder. I can also do a job for the team box-to-box.
"Any job the manager wants me to do in the centre of midfield I will do.
Osman added: "I just want to get into the team, play week in week out and help the lads.
"I am sure we will all help each other and will try to push up the league as high as we can.
"The boys did well last season. I think that this season everybody wants to kick on and improve on our performances and league standing.
"There are some good players here and, what's more, they are good lads too. They have made me feel welcome.
"The manager obviously wants to play football. He is a top man as well. He has been speaking to me all the time about how he wants me to play. Everything is going well."
Osman was poised to join Kilmarnock back in 2008 only for the move to fall through when he failed a medical.
But the England-raised player has played regularly in the last six years and stressed there are no issues with his fitness.
He said: "I had a decent season with Gretna in the top flight. But I was injured for much of the second half.
"I had a chance to join Kilmarnock. Everything was agreed, personal terms were agreed, but I had had an injury and the deal wasn't finalised.
"My first choice was to stay in Scotland and play in the Premier League. Unfortunately, that didn't materialise.
"But Northampton said they would take me and so I ended up going there.
"I was there for three seasons and played in just about every game. Since then I have been at Kerkyra in Greece and played and Crewe.
"I have played in different leagues and in different countries. I think I've done well at every club I have been at.
"Certainly, every club I have been at I have played. I have a lot of experience. I have improved as a player. Hopefully I can show my qualities at Partick Thistle."
Osman faced many of the country's biggest clubs during his stint with Gretna - including Hearts, Hibs and Rangers.
But he missed out on the Celtic game due to injury and admitted he is relishing the prospect of squaring up to the Scottish champions.
He said: "When I played in the Premier League with Gretna I played against most of the teams in the top four.
"I played against Hearts, Hibs and Rangers. Of course, they are all down in the Championship now.
"But I didn't play against Celtic. That was the only game that I missed. I was injured for that one sadly.
"I am definitely looking forward to the Celtic game. It should be a good day for the team and for the supporters."
Osman continued: "The first time I was a player in Scotland I had come straight out of non-league football.
"Mick Wadsworth gave me a big opportunity and I learned a lot from it. I didn't look back from that point on.
"Hopefully I can show how much I have improved as a player in that time."