The figures do not take into account the subsequent sales of Victor Wanyama, Gary Hooper and Kelvin Wilson, which brought in around £20m, but do encompass the purchases of Virgil van Dijk and Amido Balde earlier in the summer.
Lawwell stated that selling players remained an important part of the club's financial model, especially given the pressures facing Scottish football following the loss of Rangers from the top flight, which is without a sponsor.
The club chief, who reported a £5.2m profit from player transfers, said: "It shows the importance of Champions League football for the club and also we have made some money from the sale of players, Ki Sung-Yueng.
"This summer we have sold players and it helps make up for lost revenues elsewhere.
"Because of what we have achieved, we are under far less pressure to sell players, particularly if we get in the Champions League next season again. What we have achieved gives us more financial certainty."
Lawwell came under pressure to replace key players lost and the club were able to sign Teemu Pukki and Nir Biton just before the transfer deadline. Steven Mouyokolo and Derk Boerrigter had earlier joined new signings van Dijk and Balde.
Lawwell said: "Like everyone else, we always want to strengthen the team and the money was there to do that. We eventually got there. There were a lot of frustrations along the way, but it's not straightforward.
"It is a bit superficial saying we have £20m from the Champions League and £20m from player sales and that's £40m to spend. That's not the case because we have our cost base to pay for."