Norwich City signed 24year old left-sided midfielder Simon Lappin from St Mirren on 31st January 2007 for a fee of approxinmately £75,000. He made his City debut in the 2-1 home win over Leeds United on 3rd February 2007. Lappin had made 158 appearances for St Mirren before his transfer and had been with Motherwell as a yougnster.

Manager Peter Grant said: “Simon is a boy who has been doing very well with St Mirren. He's a natural left-sided boy, he can cover the full area of the left-hand side of the pitch and he can also play in midfield. He's a natural left-footer, and an under-21 international. I felt for the value we were getting for him it was too good an opportunity to miss. I was asking in Scotland about the left-siders and his name kept appearing - his was one name that kept coming up. Everybody spoke very highly of him.”

Lappin scored his first goal for the Canaries when he struck a 90th minute free-kick to make the score 3-2 to Norwich in their 27th February 2007 clash against Luton at Kenilworth Road.

Althoug Lappin had made 33 appearances for Norwich by January 2008, he had fallen out of favour with new manager Glenn Roeder and was loaned out to Motherwell until the end of the 2007/8 season

Lappin returned to the Norwich first team under new manager Bryan Gunn in the early part of 2009 and was rewarded with a new two year contract on 29th June 2009. He made 50 appearances in 2009/10 as the Canaries won the League One title.

Lappin signed a new contract with City on 10th January 2011 extending his stay in Norwich until June 2013. He played a key role, making 30 appearances, as Norwich won promotion in 2011/12 to the Premiership. Simon made 6 appearances in the top flight in 2011/12

On 21st November 2012, Lappin joined Malky Mackay's Cardiff on loan until 1st January 2013. He made his debut against Barnsley on 24th November 2012 but was sent-off. Lappin made a total of two appearances for Cardiff before returning to Norwich to play in their FA Cup 3rd Round win over Peterbroough on 5th January 2013.

Simon left Norwich City by mutual consent on 21st January 2013 after both parties reached the decision to help the player seek regular first team football elsewhere

Lappin signed an eighteen month contract with Cardiff City on 29th January 2013.

On 4th October 2013, Lappin joined Sheffield United on a one month loan deal. He had yet to feature for Cardiff since their promotion to the Barclays Premier League and is hoping to play regular football at Bramall Lane. Lappin said: "I am really looking forward to the challenge and this is a great opportunity for me personally. I want to play some games and help the lads out of the current predicament we find ourselves in. When you aren't playing at your club, going out on loan is a fantastic option, but first and foremost I just want to contribute to helping the lads."

Lappin was released by Cardiff at the end of the 2013/14 season, having not played for the Bluebirds in the Premier League.

Lappin trialled with Rangers in August 2014, but then signed a two year contract with St. Johnstone on 21st August 2014.

Lappin was released by St Johnstone on 18th May 2016. he had played 27 times during 2015/16 but manager Tommy Wright said "Simon and Scott Brown have been great players for me and have contributed a great deal to the club. In Simon's case, while I hope to have a little more money available at my disposal, I still have to look at the size of the squad and free up money from within to help me strengthen."

On 2nd November 2016, it was reported that Lappin was training with Conference side York City. York manager Gary Mills said "Simon is my type of footballer - if that’s the right way to put it. He is someone who is great on the ball and doesn’t give it away. He has got a good range of pass, great experience, and had a good career." This was finalised on 16th November with Lappin signing a contract until the end of the 2016/17 season. York were relegated from the Conference on 30th April 2017 with a 2-2 draw with Forest Green Rovers.

On 9th October 2017, Lappin and fellow former Canary Grant Holt signed for Ian Culverhouse's Kings Lynn Town. He made his debut as a late substitute in the 2-0 win over Hitchin in the Southern League on 10th October.

On 8th July 2018, Lappin joined Wroxham as player-coach, working under Jordan Southgate and Adam Drury.